rare earths

H A N D B O O K

O N

T H E

PHYSICS

A N D

C H E M I S T R Y

RARE EARTHS V O L U M E

7

EDITORS: K a r l A . G S C H N E I D N E R ,

Jr.

Arnes Laboratory-US DOE, and Depl. of Materials Science and Engineering Iowa State University Arnes, Iowa 50011 USA

L e R o y

E Y R I N G

Department of Chemistrv, and Center for Solid State Science Arizona State University Tempe, Arizona 85281 USA

1984

NORTH-HOLLAND AMSTERDAM, NEW YORK, OXFORD, TOKYO

O F

CONTENTS

Preface

v

Contents vii Contents of volumes 1-6 ix 51. P. Rogl Phase equilibria Silicon

in ternary and higher order Systems with rare earth elements

1

52 K . H . J . Buschow Amorphous

alloys

265

53 H . Schumann and W . Genthe Organometallic

compounds of the rare earths

Subject Index 573

Vll

446

and

C O N T E N T S O F V O L U M E S 1-6

V O L U M E 1: M E T A L S 1.

7..B. Go\dschmidt, Atomic properties (free atom}

2. B.J. Beaudry and K.A. Gschneidner, Jr., 173 3.

4. 5. 6. 7. 8. 9. 10. 11. 12.

1

Preparation and basic properties of the rare earth metals

^.YI.IAU, Electronic structure of rare earth metals

233

D.C. Koskenmaki and K.A. Gschneidner, Jr., Cerium 337 L.J. Sundström. Low temperature heat capacity of the rare earth metals 379 K.A. McEwen, Magnetic and transport properties of the rare earths 411 S.K. Sinha. Magnetic structures and ineiastic neutron scattering: metals, alloys and T.E. Scott, Elastic and mechanical properties 591 A. Jayaraman, High pressure studies: metals, alloys and compounds 707 C. Probst and J. Wittig, Superconductivity: metals, alloys and compounds 749 M.B. Maple, L.E. DeLong and B.C. Sales, Kondo effect: alloys and compounds 791 M.P. Dariel, Diffusion in rare earth metals 847 Subject Index

compounds

ill

V O L U M E 2: A L L O Y S A N D I N T E R M E T A L L I C S 13. A. landelli and A. Palenzona, Crystal chemistry of intermetallic compounds 1 14. H.R. Kirchmayr and CA. Poldy, Magnetic properties of intermetallic compounds metals

of rare earth

55

15. 16. 17. 18.

A.E. Clark, Magnetostrictive RFe^ intermetallic compounds 231 J.J. Rhyne, Amorphous magnetic rare earth alloys 259 P. Fulde, Crystal fields 295 R.G. Barnes, NMR, EPR and Mössbauer effeci: metals, alloys and

19.

P. Wächter, Europium chalcogenides: EuO, EuS, EuSe and EuTe

20. A. Jayaraman,

Valence changes in compounds Subject Index 613

compounds 507

387

575

V O L U M E 3: N O N - M E T A L L I C C O M P O U N D S - 1 21.

L.A. Haskin and T.P. Paster, Geochemistry and mineralogy of the rare earths

22. J.E. Powell, Separation chemistry 81 23. C.K. Jorgensen, Theoretical chemistry of rare earths III 24. W.T. Carnall, The absorption andfluorescencespectra of rare

earth ions in solution

25.

L.C. Thompson, Complexes

26. 27. 28. 29. 30.

G.G. Libowitz and A.J. Maeland, Hydrides 299 L. Eyring, The binary rare earth oxides 337 D.J.M. Bevan and E. Summerville, Mixed rare earth oxides 401 CP. Khattak and F.F.Y. Wang, Perovskites and garnets 525 L.H. Brixner, J.R. Barkley and W. Jeitschko, Rare earth molybdates Subject Index

209

655

IX

1

(VIj

609

17]

489

CONTENTS OF VOLUMES 1-6

X

V O L U M E 4: N O N - M E T A L L I C C O M P O U N D S - II 31.

J. Flahaut, Sulfides, selenides and tellurides

32. 33. 34. 35. 36. 37A. 37B. 37C. 37D. 37E. 37F. 37G.

J.M. Haschke, Halides 89 F. Hulliger, Rare earth pnictides 153 G. Blasse, Chemistry and physics of R-activated phosphors 237 M.J. Weber, Rare earth lasers 275 F.K. Fong, Nonradiative processes of rare-earth ions in crystals 317 J.W. O'Laughlin, Chemical spectrophotometric and polarographic methods 341 S.R. Taylor, Trace element analysis of rare earth elements hy spark source mass spectrometry 359 R.J. Conzemius, Analysis of rare earth matrices by spark source mass spectrometry "ill E.L. DeKalb and V.A. Fassel, Optical atomic emission and absorption methods 405 A.P. D'Silva and V.A. Fassel, X-ray excited optical luminescence of the rare earths 441 F. W.V. Boynton, Neutron activation analysis 457 S. Schuhmann and J.A. Philpotts, Mass-spectrometric stable-isotope dilution analysis for lanthanides in geochemical materials

1

471

38. J. Reuben and G.A. Elgavish, Shift reagents and 39. J. Reuben, Bioinorganic chemistry: lanthanides 40.

T.J. Haley, Toxocity Subject index

NMR of paramagnetic lanthanide complexes 483 as probes in Systems of biological interest 515

553

587

VOLUME 5 41. M. Gasgnier, Rare earth alloys 42. E. Gratz and M.J. Zuckermann, 43. 44.

and compounds as thin films 1 Transport properties (electrical resistivity, thermoelectric power and thermal conductivity) of rare earth intermetallic compounds 117 F.P. Netzer and E. Bertel, Adsorption and catalysis on rare earth surfaces 217 C. Boulesteix, Defects and phase transformation near room temperature in rare earth sesquioxides

321 45. O. Greis and J.M. Haschke, Rare earth fluorides 387 46. CA. Morrison and R.P. Leavitt, Spectroscopic properties

of triply ionized lanthanides in transparent

host crystals 461 Subject index 693

VOLUME 6 47. K.H.J. Buschow, Hydrogen absorption in intermetallic compounds 1 48. E. Parthe and B. Chabot, Crystal structures and crystal chemistry of 49. 50.

ternary rare earth-transition metal borides, silicides and homologues 113 P. Rogl, Phase equiUbria in ternary and higher order Systems with rare earth elements and boron H.B. Kagan and J.L. Namy, Preparation of divalent ytterbium and samarium derivatives and their use in organic chemistry 525 Subject index 567

335

Handhook on the Physics and Chemistry of Rare Barths, edited hy K.A. Gschneidner, Jr. and L. Eyring © Elsevier Science Puhlishers B. V., 1984

Chapter

53

ORGANOMETALLIC COMPOUNDS OF THE RARE EARTHS Herbert S C H U M A N N and Wolfgang G E N T H E Institut für Anorganische D-1000 Berlin

12, Fed.

und Analytische Rep,

Contents 1. Introduction and history 2. Organometallic compounds of the rare earths in the oxidation State + 3 2.1. Organometallic compounds of the rare earths containing only trligands 2.2. Cyclopentadienyl rare earth alkyl and aryl complexes 2.3. Organometallic compounds of the rare earths with allyl- and alkynyl ligands 2.4. Homoleptic alkyl and aryl derivatives of the rare earths 2.5. Organometallic compounds of the rare earths with ylide ligands

Technische

Universität

Berlin,

2.6. Organometallic compounds of the rare earths with hydride ligands 2.7. Miscellaneous compounds with bonds between a rare earth and an element other than carbon 3. Organometallic compounds of the rare earths in the oxidation State + 2 4. Organometallic compounds of the rare earths in the oxidation State +4 5. Other organometallic compounds of the rare earths 6. Catalytic application of organometallic compounds of the rare earths References

446 448 448 490 505 510 520

Symbols and abbreviations Bu C^MCs COT Cp DME Et Ind Me MeCp Ph Py THF tmed TMS d

Chemie,

Germany

dec. J m m.p. qu s subl. t 0

=C4H, =(CH3)5C5 =C,H, =C,H, = dimethoxyethane »C^Hj = indenyl = CH3 =CH,C5H4 =C,H3 pyridine = tetrahydrofuran = tetramethylethylenediamine =Si(CH3)4 = doublet signal

ß y s V V AG

445

= = = = = = = = = = = = = = = =

decomposition point coupling constant multiplet Signal melting point quartet signal singlet Signal Sublimation point triplet Signal Center of a ring C H ring deformation Vibration C H ring deformation Vibration chemical shift infrared stretching Vibration bonds to the metal ring deformation frequency activation energy

527 535 547 558 560 564 565

446

H. SCHUMANN and W. GENTHE

1. Introduction and history A malodorous spontaneously inflammable hquid, which is formed from the pyrolysis of arsenous oxide with potassium acetate, was described as Cadet's Fuming Liquid in 1760 (Cadet de Gassicourt, 1760), marking the starting point of Organometalhc Chemistry. It was not until 100 years later that Cahours and Rieche (1854) established the correct formula for this first compound having a covalent a-bond between carbon and a metalloid, arsenic. The first genuine organometallic compound containing a metal-carbon a-bond, ethyl zinc iodide, was prepared by Frankland (1849). This publication ignited the fascinating evolution of organometallic chemistry between 1850 and 1950. However, the only compounds that were characterized during this period were those that contained a-bonds between carbon and certain metal atoms, specifically metals which contained completely empty or completely filled d-orbitals, main group elements or elements of the zinc group. The first example of a completely characterized organo-transition-metal complex was C j H 5 T i ( O C 3 H 7 ) 3 L i O C 3 H 7 L i B r ( C 2 H 5 ) 2 0 prepared by Herman and Nelson (1952), although Zeise's Salt, K[Pt(C2H4)Cl3] was noted i n the 19th Century (Zeise, 1827). In contrast to the a-bonded organometallic compounds of the main group elements, all organometalhc compounds of the transition metals containing metalto-carbon a-bonds are mostly thermal, air and moisture sensitive substances. This feature can be explained by the high reactivity of these compounds due to the incompletely filled d-orbitals. Whereas the main group metals form stable metal-tocarbon a-bonds if the element has eight electrons available for bonding, the transition metals need eighteen electrons. This Situation becomes even more comphcated, when one goes from the transition metals to the lanthanides, which involve 4f-orbitals in their outer valence shells, creating sixteen outer Orbitals that have to be occupied by thirty two electrons. Therefore problems in preparing organometallic compounds of the lanthanides are to be anticipated. V o n Grosse (1925) postulated the nonexistence of alkyl or aryl derivatives of the lanthanides. In this article the term organometallic compound includes alkyl and aryl derivatives of the rare earths—the transition metals of group III, scandium, yttrium, lanthanum and the lanthanides cerium to lutetium with covalent metal-to-carbon a-bonds, as well as the so-called 77-complexes with more than monohapto metal-tocarbon bonds, for example cyclopentadienyl and olefin complexes, metal acetylides, but not carbonyls, cyanides and isocyanide complexes. Derivatives of scandium, yttrium and lanthanum are included and discussed together with the compounds of the lanthanides, because of many similarities in the synthesis and the chemistry of these organometallic derivatives of the rare earths. The common oxidation State of the rare earth elements is +3. Therefore organometallic compounds of the type R L 3 (R = rare earth metal, L = ligand) will be diamagnetic for R = Sc, Y , L a and L u , but paramagnetic for the other lanthanides. The redox properties of some of the lanthanides, reflecting the electronic Situation with an unfilled, half-filled, or completely filled f shell make the existence of organometallic compounds with the lanthanides in the oxidation State + 2 and + 4 possible, namely E u L j , Y b L j , and CeL4.

ORGANOMETALLIC COMPOUNDS OF THE RARE EARTHS

447

The rare earths are rather electropositive elements and are hard acids following the Pearson concept (Pearson, 1973). This causes, in combination with the contracted nature of the 4f-orbitals of the lanthanides, poor overlap with ligand Orbitals and therefore high ionic character in the metal-to-carbon bonds. Large ionic radii especially of the lanthanide ions give rise to organometallic compounds in which the metals have higher coordination numbers than normally found with transition metals. Because of the lanthanide contraction, lanthanum has the largest ionic radius of 1.061 Ä for L a ^ ^ , lutetium has the smallest of the 0.848 Ä for Lu^"" (see table 1; Templeton and Dauben, 1954). The first indications of the existence of an organometallic compound of the rare earths was the work of Rice and Rice (1935). Using the Paneth technique, free radicals were reacted with a variety of metals, including lanthanum. But no mention was made of the isolation or Identification of any of these alkyl lanthanum species. Three years later, Plets (1938) described the first organometallic compounds of the rare earths. Triethyl scandium and triethyl yttrium etherates were prepared from ScClj and Y C I 3 by their reaction with ethyl magnesium bromide. However this work is questionable, since it could not be repeated by other scientists (Jones, 1942; Gilman and Jones, 1945; Afanasev and Tsyganova, 1948). In connection with the Manhattan Project Gilman and Jones (1945) described the next attempts to prepare organometallic compounds of the lanthanides. They found biphenyl was produced either from the reactions of LaCl3 with L i Q H j in ether, or from lanthanum with diphenyl mercury at 135°C in a sealed tube for 100 days. The discovery of ferrocene and of the other sandwich complexes initiated a new field of organometallic chemistry, the chemistry of the 7r-complexes. Wilkinson and Birmingham (1954) prepared the first organometallic 77-complexes of the rare earths, the tricyclopentadienyl complexes of Sc, Y , L a , Ce, Pr, N d , Sm and G d . It was not until 14 years later with the synthesis of triphenyl scandium (Hart and Saran, 1968) that the first a-bonded aryl-rare-earth compound was made. Organometallic chemistry of the rare earths has become an area of vigorous activity in the last decade. This area of organometallic chemistry, which was ignored

Table1

Crystal radii of the rare earth ions R^* in Ä. Sc' + La^ + Ce' + Nd^ + Pm^ + Sm' + Eu' +

0.68 0.88 »' L061 1.034 "* 1.013 0.995 0.979 0.964 0.950

Zachariasen (1954). Templeton and Dauben (1954).

Gd' + Tb^ + Dy' + Ho-'* Er' + Tm' + Yb^ + Lu'* '•' Estimated.

0.938 "> 0.923 *" 0.908 0.894 0.881 0.869 >" 0.858 0.848


448

for a long time, is very promising from the theoretical viewpoint as well as from their use as reagents or catalysts in synthetic chemistry. A number of review articles covering this area of chemistry appeared in recent years (Gysling and Tsutsui, 1970; Hayes and Thomas, 1971; Kanellakopulos and Bagnall, 1972; Tsutsui et al., 1976; S.A. Cotton, 1977; Marks, 1978a; Schumann, 1979a, b; Marks and Ernst, 1982). Since 1964 there is an annual survey available, covering the literature in the field of organometallic chemistry of the rare earths and of the actinides (Seyferth and King, 1965, 1966, 1967; Calderazzo, 1968, 1969, 1970, 1972, 1973, 1974; Marks, 1974, 1975, 1976, 1977, 1978b, 1979, 1980, 1982). A n excellent article containing all the knowledge on organometallic compounds of the rare earths with a literature closing date of the end of 1981 but with many references from recent publications including Conference reports appeared in the Gmelin Handbook of Inorganic Chemistry (Forsberg and Moeller, 1983).

2. Organometallic compounds of the rare earths in the oxidation state + 3 2.1.

Organometallic

compounds of the rare earths containing

only Tr-ligands

2.1.1. Cyclopentadienyl complexes Cp^R, CpjRX, CpRXj The tris(cyclopentadienyl) complexes of the rare earths were the first compounds discovered and the most intensively investigated class of organometallic compounds of these elements. They were reported for the first time in 1954 by Wilkinson and Birmingham, and generally prepared by reaction of anhydrous rare earth trichlorides with sodium cyclopentadienide in tetrahydrofuran at room temperature and isolated by subhmation of the crude products in vacuum at about 220°C (Wilkinson and Birmingham, 1954; Krasnova et al., 1971): RCI3 + 3 N a C s H j

THF

( C 5 H 5 ) 3 R T H F + 3 NaCl,

(1)

* (C5H5)3R + T H F .

(2)

220°C

(C5H5)3RTHF

10"-' torr

To prepare the radioactive (C5H5)3Pm another method was developed, using molten Mg(C5H5)2 or molten Be(C5H5)2 as solvents and cyclopentadienide precursor, to avoid the problems of a-radiolysis of the solvent (Kopunec et al., 1969; Lauberau and Bums, 1970). The high vapor pressure of these starting materials allows easy removal of them from the reaction mixture. The same method, using rare earth trifluorides and triiodides was also used for the synthesis of the tricyclopentadienides of scandium, cerium, samarium and neodymium (Reid and Wailes, 1966; Atwood and Smith, 1973a), and the promethium compound has also been prepared by neutron bombardment of the neodymium complex (Baumgärtner et al., 1967). 2 PmCl3 + 3 Mg(C5H5)2 ^ 2 (C5H5)3Pm + 3 M g C l j , 'Nd(C3H3)3-

(n, Y)

'Nd(C3H3)3-.'îPm(C3H5)3.

(3) (4)


449

Another method available for the synthesis of such derivatives is the reaction of the rare earth trichlorides with K C 5 H 5 or T I C 5 H 5 i n benzene (E.O. Fischer and H . Fischer, 1965b; Manzer, 1976a). This method allows the synthesis of tris(cyclopentadienyl) europium, which could not be prepared by the reaction in tetrahydrofurane, because of the decomposition of (C5H5)3Eu T H F during Sublimation: benzene , RCI3 + 3 K C 5 H 5

• (C5H5)3R-I-3 K C l .

(5)

The synthesis of (C5H5)3Eu has also been described by Tsutsui et al. (1966) by the reaction of CpEuCl2 • (THF)3 and N a C p followed by careful removal of T H F . The tris(cyclopentadienyl) compounds of the rare earths have high thermal stability and a definite melting point. They are sensitive to moisture and air, and hydrolyze forming the rare earth hydroxides and cyclopentadiene. The reactions with alcohols are similar giving rare earth alkoxides (Maginn et al., 1963). The magnetic moments, which are nearly identical with the R^^ ions in aqueous solution, as well as the reaction of the complexes with F e C l j , yielding ferrocene, speak for a high degree of ionic character i n the rare-earth-to-cyclopentadienyl bond ( B i rmingham and Wilkinson, 1956). The rare earth tricyclopentadienyls are insoluble in aliphatic hydrocarbons, and only sparingly soluble in aromatic hydrocarbons. They dissolve i n polar solvents like tetrahydrofuran with complexation. Similarly, numerous bases like ethers, amines, isonitriles, phosphines and other compounds react with C p j R , yielding stable 1:1 complexes. The solubihty of the compounds C p j R i n tetrahydrofuran was studied between 15 and 60°C by Borisov et al. (1975). From the temperature dependence of the solubility the heat of dissolution was determined to be about 5 k c a l / m o l e for all of the tris(cyclopentadienyl) compounds of the rare earths. The vapor pressure and the temperature of the triple point of the tricyclopentadienyls of the rare earth elements Y , L a , Ce, Pr, N d , Sm, G d , Tb, D y , H o , Er, T m , Y b and L u have been measured i n the temperature ränge of 195 to 390°C and the heats of Sublimation were calculated from the temperature Variation of the vapor pressure (Borisov et al., 1973; Duncan and Thomas, 1964; Hang, 1971; Devyatykh et al., 1972, 1973a). The volatiüty increases with increasing atomic number, the Sublimation temperature decreases. The enthalpy of combustion and formation as well as the mean dissociation energies of the cyclopentadienyl-metal bonds have been measured for the (C5H5)3R compounds of Sc, Y , L a , Pr, T m and Y b , showing a decrease of the bond energy with increasing atomic number (Devyatykh et al., 1974b). The colors and some physical properties of the rare earth tricyclopentadienides are given i n table 2. Tricyclopentadienyl rare earth compounds form stable 1:1 adducts with many bases. T H F adducts have been described for yttrium, lanthanum and nearly all lanthanides (Manastyrskyj and Dubeck, 1964; Calderazzo et al., 1966; E . O . Fischer and H . Fischer, 1966; R . D . Fischer and H . Fischer, 1967; Pappalardo, 1969; Raymond and Eigenbrodt, 1980; Rogers et al., 1981; Deacon et al., 1982). Tetrahydrofuran can be removed in high vacuum from all the complexes except for

450

H. SCHUMANN and W. GENTHE Table 2

Physical properties of rare earth Iricyclopentadienides. Compound

Color

Melting point (°C)

(CsH^jjSc

straw pale yellow colorless orange

240 295 395 435

pale green reddish blue yellow-orange orange brown pale yellow colorless yellow yellow pink green-yellow dark green colorless

415 380

/'cff (B.M.) diamag. diamag. diamag. 2.46 2.30 3.61 3.62

365

1.54

(C5H5)3La (C5H5)3Ce (C,H5),Pr (C5H5),Nd (C5H3)3Pm (C5H5)3Sm (C5H3)3EU (C5H3),Gd (C3H5)3Tb (C3H3)3Dy (C3H3)3Ho (C5H5)3Yb 1. 2. 3. 4. 5. 6.

350 316 302 295 285 278 273 264

7.98 8.9 10.0 10.2 9.44 7.1 4.00 diamag.

Refs. 1 1 1 2 6 2 2 3 2 4 2 5 2 5 2 5 2 5

Wilkinson and Birmingham (1954). Birmingham and Wilkinson (1956). Lauberau and Burns (1970). Tsutsui et al. (1966). E.O. Fischer and H. Fischer (1965b). Deacon et al. (1983c).

(C5H5)3Eu • T H F . The T H F complexes exhibit a bathochromic shift in their color because of the coordination of the oxygen to the rare earth metal. Tetrahydrofurane adducts with 2 and 3 T H F coordinated to the tricyclopentadienyl lanthanide complex are also known (Suleimanov et al., 1982c). Tricyclopentadienyl rare earth cyclohexyl isonitrile complexes have been prepared by addition of cyclohexyl isonitrile to the corresponding tris(cyclopentadienyl) rare earth compounds in benzene. They show definite melting points and are sublimable in vacuum at about 150 to 160°C (E.O. Fischer and H . Fischer, 1965a, 1966; V o n Ammon and Kanellakopulos, 1972): (C5H3)3R+QH„NC^(C5H3)3R-CNQH„,

(6)

R = Y , L a , Ce, Pr, N d , Sm, Eu, G d , Tb, Dy, H o , Er, T m , Y b , L u . Tricyclopentadienyl ytterbium reacts with liquid ammonia with formation of a stable 1 :1 complex, which can be sublimed, but which decomposes above 200°C with formation of dicyclopentadienyl ytterbium amide and cyclopentadiene (E.O. Fischer and H . Fischer, 1966). The corresponding 1 :1 adducts of N H 3 could also be isolated for (C5H5)3Pr and (C5H5)3Sm (Birmingham and Wilkinson, 1956), as well


451

as 1 :1 complexes of several rare earth tricyclopentadienyls with pyridine ( R . D . Fischer and H . Fischer, 1965), methylpyrrolidone (Von A m m o n et al., 1969), nicotine (Von Ammon et al., 1969), hydrazine (Hayes and Thomas, 1969b), and pyrazine (Baker and Raymond, 1977). Triphenylphosphine forms a stable adduct with tricyclopentadienyl ytterbium (E.O. Fischer and H . Fischer, 1966), and also tributylphosphine gives an analogous 1 :1 complex with the same lanthanide complex ( R . D . Fischer and Bielang, 1980b); however, attempts to prepare such complexes of tricyclopentadienyl ytterbium with P P h j H , PPhH^, P ( Q H , , ) 3 , P ( Q H , , ) j H , P ( Q H „ ) H 2 , PMe2Ph, P(t-Bu)2Cl, as well as with some isonitriles like C H 3 N C , Q H ^ N C , 4 - M e Q H 4 N C , and 4 - C I Q H 4 N C yielded only Solutions of these adducts in pentane or toluene, which decomposed during the evaporation of the solvents (Bielang and Fischer, 1978). Tricyclopentadienyl ytterbium reacts with tricyclopentadienyl uranium fluoride in benzene with formation of an adduct with a fluorine bridge between ytterbium and uranium. Tricyclopentadienyl thulium does not give an analogous complex with C P 3 U F . These reactions are unique to the uranium-fluorine bond for C p j U C l falls to give an adduct with Cp3Yb (Kanellakopulos et al., 1970). The Lewis acidity of tricyclopentadienyl rare earth compounds was investigated by reactions with some transition-metal carbonyl and nitrosyl complexes. Infrared spectra showed coordination only between CrCp(NO)2Cl and C p j E r or Cp3Yb, and in the case of (MeCp)3Sm only with a large excess of the base. Spectral changes in the infrared and ' H N M R spectra of MnCp(CO)3, M C p ( C O ) 2 N O with M = Cr, Mo, W, Co2(CO)g and [NiCp(CO)]2 in the presence of some tricyclopentadienyl rare earth complexes indicate coordination at both the C O and the N O ligands, with stronger Lewis basicity for N O and the bridging C O groups in comparison with the terminal C O groups. However, Cp2YbCl and (MeCp)2YbCl gave no coordination with the nitrosyl or with the carbonyl complexes already described (Crease and Legzdins, 1972, 1973b). The interaction of Cp3Sm with a number of anions [Mn(CO)5_„L^]^ also causes a shift of the i ' C O upon coordination. Infrared and ' H N M R measurements indicate that the oxygen atom functions as the Lewis base in complexes with [Mn(CO)5_„L„]Br, while the manganese atom was the site of basicity in anions of the type [ M n ( C O ) 5 _ „ { P ( O P h ) 3 ( O n a k a and Furuchi, 1979). IR spectra of the reaction mixtures of Cp3Sm and C r C p ( C O ) 2 N O , (FeCpNO)2, [CrCp(NO)2]2, [Mn(MeCp)]3(NO)4 and [(MeCp)Mn(CO)NO]2 displayed bands diagnostic of Cp3Sm coordinated to terminal, two-metal bridging, and three-metal bridging N O (Onaka, 1980). Rare earth tricyclopentadienides like Cp3Yb react with a number of protic acids like yS-diketones, /ß-ketoimines. alkynes, indene and fluorine with formation of unstable complexes and in some cases of definite products (see sections 2.3 and 2.7.1) (R.D. Fischer and Bielang, 1980b). The isolated complexes of tricyclopentadienyl rare earth compounds are shown in table 3. Dicyclopentadienyl rare earth chlorides can be prepared by treating the rare earth trichlorides with two equivalents of cyclopentadienyl sodium or with its respective tricyclopentadienyl derivative in tetrahydrofuran (Maginn et al., 1963; Schumann

452

H. SCHUMANN and W, GENTHE Table 3

Complexes of tricyclopentadienyl rare earth compounds. Complex CpjY-CTHF) Cp,La(THF) Cp3Pr(THF) CpjNd-CTHF) CpjSm-CTHF) Cp,Eu(THF) Cp3Gd(THF) Cp3Tb(THF)

Color white white

Other data subl. 160-180°C/10"' subl. 260°C/10~'

brown dark green luminescence spectra

CpjHo (THF) Cp3Er(THF) Cp3Tm(THF) Cp3Yb(THF) Cp3Pr-(NH3) Cp3Sm(NH3) Cp3Yb-(NH3) Cp,Yb(C5H5N) Cp3Yb2(N,H4) Cp3Nd(MeNC4H8) (Cp3Yb)2-(C4H4N2) Cp3Pr[(-)-nicotine] CpjNd • [(-)-nicotine] Cp3Tm-[(-)-nicotine] Cp3YbPBU3 Cp3YbP(t-Bu)2Cl Cp3YbP(C,H„), Cp3YbPH(C,H„)2 Cp3YbPH2(CeH„) Cp3YbPPh3 Cp3Yb PHPhj Cp,Yb PHjPh Cp3YbPMejPh Cp3YbCNMe CpjYbCNPh Cp,YbCNC,H4-4-Cl Cp3YCNC,H„ Cp3LaCNC (Cp2YCl)2 • A I H 3 • E t 2 0 .

(16)

X-ray structures have been investigated of many cyclopentadienyl derivatives of the rare earths. Among the tricyclopentadienyl compounds, the structures of the Sc and the Sm derivative have been solved. The structure of CP3SC, which is orthorhombic with space group Pbc2,, is shown in fig. 1 (Atwood and Smith, 1973a). It shows four molecules in the unit cell with an infinite chain arrangement of the CP3SC


455

Table 4

Physical properties of cyclopentadienyl rare earth halides. Compound

Color

Other data

Cp^ScCl Cp^YCl CpjSmCl

green-yellow colorless yellow

m.p. subl. m.p.

CpjGdCl

colorless

m.p.

CpJbCl CpjDyCl

yellow

CpjHoCI

yellow-orange

CpÊrCl

pink

CpjTmCl CpjYbCl

green-yellow orange-red

CpjLuCl Cp2ScCl(THF) Cp2GdCl(THF) Cp2YbCl(THF) Cp2LuCI(THF) CpjYCn-COjAlMcj (Cp^YCl), AlHjEtjO CpGdClj CpYCl,(THF)3 CpSmClj (THF)3

white white

CpEuCl2(THF)3

purple

m.p. dec. m.p.

CpGdCl2(THF)3 CpDyCl2(THF)3

lavender colorless

m.p. m.p.

CpHoClj(THF)3 CpErCl2-(THF)3

yellow pink

CpYbCl2(THF)3

orange

CpLuCl2(THF)3 CpjErl CpjNdCN CpjYbCN [Cp2YCIAlH3NEt3]2 CpLaCl2(THF)3 CpLaCl2(THF)4 CpSmCl2(THF)4 CpEuCl2(THF)2

colorless pink blue yellow colorless

m.p. m.p. feff m.p. Ce« dec. m.p. subl.

50°C (dec.) SO'C 50°C (dec). 4.24 B.M. 82-86°C (dec.) 85-90°C (dec). 11.81 B.M. 84-92°C 91-94°C, 9.68 B.M. 78-81°C, 7.52 B.M. 70-72°C 76-78°C 150-250°C/10-^

dec.

65°C

dec.

60°C

IR m.p. Meff m.p. Mcff m.p. M^ff IR subl. m.p. Meff IR m.p. m.p. Meff

Refs. 313-315°C 250°C/10"' 200°C (dec). L62 B.M. UO'C (dec), 8.86 B.M. 343-346°C, 10.6 B.M. 340-343°C, 10.3 B.M., IR 200°C (dec). 9.79 B.M. 200°C/10"'' 240° C (dec), 4.81 B.M. 318-320°C 303-307°C, 8.18 B.M.

white

beige

1 2 3 3 3 3 14 3 3 3 3,14 3 3 14 2 3 3 14 3 5 6 6 7 8 9 10 11 12 16 12 12 12 12 12 12 12 12 12 12 16 12 3 13 13 15 16 17 17 16

456

H. SCHUMANN and W. GENTHE Table 4 (continued)

Compound

Color

Other data

CpEuCl2(THF)4 CpTmCl2(THF)3 CpTmCl2(THF)4 CpYbCl2-(THF)4

dec. dec.

1. 2. 3. 4. 5. 6. 7. 8. 9.

10. 11. 12. 13. 14. 15. 16. 17.

Coutts and Wailes (1970). Holton et al. (1979b). Maginn et al. (1963). Schumann and Jarosch (1976). Manzer (1976). Gomez-Beltran et al. (1975). Schumann and Genthe (1981). Holton et al. (1979c). Lobkovskii et al. (1982).

Refs. 58-64°C 76-80°C

17 16 17 17

Dubois et al. (1977). Jamerson et al. (1974). Manastyrskyj et al. (1963). Kanellakopulos et al. (1974). Changtao Qian et al. (1983). Lobkovskii et al. (1983). Suleimanov et al. (1982c). Suleimanov et al. (1982d).

units, in which each scandium is bound to two Tj'-cyclopentadienyl hgands with an average scandium-carbon bond length of 2.49 Ä and two bridging rj'-cyclopentadienyl ligands with an average S c - C bond length of 2.57 A . For the tj'-cyclopentadienyl groups, the angles of the S c - C bonds with the plane of the rings are 61° and 73°. For tricyclopentadienyl samarium Wong et al. (1969) describe an orthorhombic space group Pbcm with eight formula units per unit cell (fig. 2). However, this structure has been disputed by Atwood and Smith (1973a). But also this structure shows two symmetrically independent and structurally different groups of chains with samarium atoms surrounded by two »j^-bound cyclopentadienyl ligands and two tj'-bound cyclopentadienyls showing similar bonding distances. In addition to these two structures, the unit cell dimensions of the tricyclopentadienyl derivatives of Pr, Pm, Sm, G d , Tb and T m have been determined and compared with each other by

Fig. 1. Structure and unit cell packing of Sc(C5H5)3 (after Atwood and Smith, 1973a).


457

Fig. 2. The molecular structure of Sm(C5H5)3 (after Wong et al., 1969).

«+*/2

Lauberau and Burns (1970) (table 5). They show that the tricyclopentadienyls of Pr, Pm, Sm, G d and Tb are isomorphous, but tricyclopentadienyl thulium is not . Its Single crystal diffraction study showed systematic absence for the space group Pnma or Pna2,. The Single crystal X-ray analysis of sublimated tricyclopentadienyl praseodymium (Hinrichs et al., 1983) shows a singular polymeric chain structure with three rj^-coordinated cyclopentadienyl rings and one rj^-coordinated ring for every Pr atom. The formal coordination number of Pr is 11, which is in contrast to tricyclopentadienyl scandium, where Sc has a coordination number of only 8. A s expected the bonding distances of the bridging C 5 H 5 ring become larger with respect to the other C 5 H 5 groups. Table 5

Unit cell dimensions of rare earth tricyclopentadienyls. Compound (C5H5)3SC (C5H5)3Pr (C5H5)3Pm (C5H5)3Sm

Radius M * ' (Ä) 0.68 1.013 0.979 0.964

(C5H5)3Gd (C5H5)3Tb (C5H5)3Tm

0.938 0.923 0.869

Atwood and Smith (1973a). Lauberau and Bums (1970). Wong et al. (1969).

a

b

c

(A) 12.881(5) 14.20 14.12 14.23(2) 14.15 14.09 14.20 19.98

(A) 8.954(4) 17.62 17.60 17.40(1) 17.52 17.52 17.28 13.82

(A) 9.925(4) "> 9.79 9.76 9.73(2) " 9.77 *" 9.65 9.65 '» 8.59

458

H. SCHUMANN and W. GENTHE C1i

C13

C34

C33

Fig. 2a. Molecular structure of (C5H5)3Pr (after Hinrichs et al.. 1983).

The structures of the adducts of tricyclopentadienyl rare earth complexes with tetrahydrofuran and cyclohexylisonitrile show monomeric units with three •»j'-bound cyclopentadienyl ligands (figs. 3 and 4). The unit cell parameters of the three isomorphous tetrahydrofuran complexes of tricyclopentadienyl yttrium, lanthanum and gadohnium (Rogers et al., 1980, 1981) together with their main bonding distances and bonding angles are given in table 6 as well as the unit cell parameters and some bonding distances of tricyclopentadienyl praseodymium cyclohexyl isonitrile (Burns and Baldwin. 1976). The centrosymmetric complex of two cyclopentadienyl ytterbium molecules with one pyrazine ligand crystallizes in the space group C 2 / c with the unit cell dimensions: a = 14.006(5) A,b = 8.299(3) Ä, c = 24.637(9) Ä, and ß = 102.83(1)° with four molecules in the unit cell (fig. 5.) (Baker and Raymond, 1977). The coordination Table 5a

Unit cell parameters, bond lengths and angles of tricyclopentadienyl praseodymium. Space group a(A)

P2 8.314(8) 9.714(5) 8.372(5) 116.06(6) 2

b(A)

c(Ä) (deg) Z ß

bond lengths (A)

bond angles

(deg)

Pr-0l Pr-0 2 Pr-0 3

01-Pr-0 2 01-Pr-0 3 0 2-Pr-0 3 Pr-C24-Pr' Pr-C23-Pr'

111.63 119.17 116.79 141.74 161.96

2.526 2.602 2.488 Pr-C24 2.966(11) Pr-C23 2.892(12) Pr'-C24 3.130(12) Pr'-C23 2.940(12)


459

Fig. 3. Molecular structure of (C5H5)3Gd-THF (after Rogers et al., 1980). around the ytterbium atoms is nearly C,^ with angles of the centers of the cyclopentadienyl rings to ytterbium to the nitrogens of pyrazine of 118° and 98.5° average. Pertinent bond distances are: Y b - C = 2.684(11) Ä, and Y b - N = 2.61(1) Ä. Metal-metal interactions could not be detected by magnetic investigations.

Fig. 4. Stereoscopic view of the structure of (C5H5)3Pr-CNCf,H,, (after Burns and Baldwin, 1976).


460

Table 6

Unit cell parameters, bond lengths and angles of tricyclopentadienyl rare earth complexes.

Space group a{A) b(k)

e(Ä) (deg)

ß

Cp3Y(THF)

Cp3La(THF)

Cp3Gd(THF)

Cp3PrCNC,H,,

P2,/n 8.170(3) 24.595(5) 8.260(3) 101.32(3)

P2,/n 8.371(4) 24.636(5) 8.454(3) 101.84(3)

P2,/n 8.220(4) 24.650(9) 8.317(4) 101.39(3)

P2,/n 8.298(3) 21.66(1) 11.943(4) 104.98(3)

bond lengths (A) R-01 R-0 2 R-0 3 R-O Pr-C22

2.438 2.453 2.454 2.451(4)

2.575 2.575 2.576 2.57(1)

2.47 2.49 2.49 2.494(7)

2.78 " 2.79 » 2.77'> 2.65(1)

bond angles (deg) 01-R-02 0 2-R-0 3 0 1-R-O 0 2-R-O Pr-C22-N

119.2 115.4 96.4 100.8

120 116 96.2 102.2

" Average distance Pr-C„„g ,, Pr-C^,„^

118.6 117.0 96.3 101.0 171.1(1.1)

Pr-C„„|

The yellow green crystals of the dimeric dicyclopentadienyl scandium chloride show six dimeric molecules in the unit cell of the monoclinic space group P 2 , / c with a = 13.54(1) Ä, = 16.00(1) Ä, c = 13.40(1) Ä, and = 93.97(5)°. Four chlorinebridged dimers he in general positions, the other two on a center of symmetry. There are two crystallographically different molecules in the cell which do not differ

Fig. 5. Structure of (C5H5)3YbNC4H4NYb(C5H5)3 (after Baker and Raymond, 1977).


461

Fig. 6. Molecular structure of [(C,H5)2ScCl]2 (after Atwood and Smith. 1973b). significantly in any respect. The cyclopentadienyl rings form a Tj^-bond with S c - C bond lengths between 2.39 and 2.49 A . The scandium-chloride bond lengths average 2.575 Ä with a C l - S c - C l angle averaging 81.5° (fig. 6) (Smith and Atwood, 1972; Atwood and Smith, 1973b). The crystal structure of cyclopentadienyl erbium dichloride tris(tetrahydrofuranate) (fig. 7) shows formally eight-coordinated erbium, but is more accurately described as an octahedral erbium atom with an rj'-cyclopentadienyl ring (average E r - C distance = 2.667 Ä) occupying a Single polyhedral vertex; the T H F ligands have a meridional disposition ( E r - O distances are 2.350, 2.365 and 2.452 Ä), and the chloride ligands occupy trans sites of the octahedron with E r - C l bond lengths of 2.613 and 2.620 Ä. The main bond angles are: C l - E r - C l : 154.85(4)°,

Fig. 7. The molecular structure of C5H5ErCl2(THF)3 (after Day et al., 1982).

462


0 C p - E r - O ( c i s ) : 102.5(2)°, 0 C p - E r - 0 ( t r a n s ) : 179.3(1)°. The major distortion in this structure is a displacement of 0.54 A of the Er atom out of the equatorial plane toward the cyclopentadienyl ligand. The unit cell dimensions for the monoclinic compound (space group P 2 , / n ) are: a = 7.822(2) k, b= 17.096(4) Ä, c = 15.162(3) Ä, and ;8 = 95.80(2)° (Day et al., 1982). The 2 : 1 : 1 complex of dicyclopentadienyl yttrium chloride, aluminum hydride and ether forms rhombic crystals of space group Pcab with the unit cell dimensions 0 = 13.521(5) Ä, ft = 12.877(5) Ä, 300°C m.p. >3(X)°C

220-223°C 114°C

m.p. > 3 0 0 ° C m.p. >3(X)°C

m.p.

221-230°C

471

472

H. S C H U M A N N and W. G E N T H E Table 8 (continued)

Compound

Color

(C5Me5)2YbCl-py (C,Me5)2Yb(M-Cl)2AlCl2

purple blue green purple/violet violet violet violet purple white white blue

(C5Me5)2Yb(M-Cl)2Li(Et20)2 (C5 Me,) 2Yb( /n-Cl) 2 Li • (tmed) (C5 Me,) 2Yb(M-Cl) 2 Na • (Et 2O) 2 (C5 Mcs) 2Yb( M-Cl) 2 Na • (tmed) (C5Me5)2Yb(;U-I)2Li(Et20)2 (C5 Me,) 2 Lu( /i-Cl) 2 AlCl 2 (C5 Me,) 2 Lu( M-Cl) 2 Li • (Et 2O) 2 C5Me5Nd(ft-Cl)3Na-(Et20)2 C5Me5Yb(M-Cl)3Li(Et20)2 C5Me5Yb(M-Cl)3LiTHF

Other data m.p. m.p.

270-272°C 175°C

dec. dec. dec. dec.

I30°C 255°C 280°C 120°C

dec.

125°C

m.p. m.p.

183-185°C 187-190°C

blue

green C5Me5Yb(^-I)3Li(Et20)2 white C5 Me, Lu( M-Cl) 3 Li • (Et 2O) (CsMe4Et)2Y(M-Cl)2Li (Me3SiC5H4)2YCl colorless (Me3 SiC, H 4) 2Y( f Z z p

8

distances (A) Sc-Cl Sc-C

2.58 2.51

Pr-Cl Pr-C Pr• • • Pr

2.81 2.76 4.372(1)

Yb-Cl Yb-C

2.65 2.62

Nd-Cl Li-Cl Nd...Li

2.744 2.405 3.63(3)

0 m z H X m

angles (deg)

^ er ^ 1

ä

Cl-Sc-Cl Sc-Cl-Sc

79 101

Cl-Pr-Cl Pr-Cl-Pr

Cp'-Sc-Cp'

131

Cp'-Pr-Cp'

78 102 130

Cl-Yb-Cl Yb-Cl-Yb Cp'-Yb-Cp'

80 100 130

Cl-Nd-Cl Cl-Li-Cl

82.1 97.2(9)

o 2

O R G A N O M E T A L L I C COMPOUNDS OF T H E R A R E EARTHS

479

The X-ray structure of {[(Me3Si)2C5H3]2PrCl}2 (fig. 15), as well as the corresponding isostructural scandium and ytterbium derivatives show distorted tetrahedrally coordinated rare earth metals. Some detailed data are given in table 10, including the data for the complex [(Me3Si)2C5H3]2Nd(M-Cl)2Li • (THF)2 (fig. 16). This bis[(trimethylsilyl)cyclopentadienyl] tetrahydrofuran complexes of yttrium, lanthanum and neodymium chloride react with tetramethylethylenediamine as well as with dimethoxyethane with exchange of the coordinated tetrahydrofurane, yielding new complexes with the chelating tmed and D M E hgands coordinating the Uthium atoms (Läppert et al., 1981b). The dimers [{(Me3Si)2C5H3}2RC1]2 react with chlorides of large cations M C I with formation of stable complexes [M][({Me3Si)2C5H3 }2RCl2] which decompose on melting at about 165 to 175°C (Läppert et al., 1983a): 2MCl-l-[{(Me3Si)2C5H3}2RCl]2-^2[M][{(Me3Si)2C5H3}2RCl2], M M M M

= = = =

(26)

N(PPh3)2, R = Y ; PPh4, R = Pr, Tm; AsPH4, R = N d ; PPh3(CH2Ph), R = N d , D y .

The molecular structure of [AsPh4][((Me3Si)2C5H3 }2NdCl2] consists of discrete triclinic monomers, space group P l [a = 12.334(4) A , b = 13.924(4) Ä, c = 15.844(5) Ä, a = 91.60(3)°, ß = 97.96(3)°, y = 104.35(3)°, Z = 2], in which the anion (fig. 17) shows the following bond lengths and angles: N d - C l ( l ) 1.669(3) Ä, N d - C l ( 2 ) 2.667(3) Ä, N d - C (aver.) 2.78 Ä, C l ( l ) - N d - C l ( 2 ) 99.3(1)°, 0 C p ( l ) - N d - 0 Cp(2) 126.3°.

O R G A N O M E T A L L I C C O M P O U N D S OF T H E R A R E E A R T H S

481

Table11 Crystallographic data and important bond distances and angles in Nd[C5H3(CH3)2] _

Space group a(Ä) b(k) c{A) a (deg) ß(deg) Y(deg) Z distances Nd-C Nd-C Nd-C Nd-C Nd-C

A(l) A(2) A(3) A(4) A(5)

Cj-PI 12.793(7) 13.012(4) 8.419(5) 91.42 (4) 107.29 (4) 118.90 (4) 2 (A) 2.800(22) 2.859(15) 2.766(15) 2.836(17) 2.748

angles

(deg)

0A-Nd-0B 0A-Nd-0C 0B-Nd-0C

119.9(3) 119.8(4) 120.4(3)

Some analogous complexes with the cyclopentadienyl ligand substituted only by one organosilyl group have also been described. Atwood et al. (1978) report the colorless compounds (Me3SiC5H4)2Y(M-a)2Li • ( T H F ) ^ and (Me3SiC5H4)2Y(fi.Cl)2Li • (tmed), and the crystalhne dimer [(Me3SiC5H4)2YCl]2, which was obtained after subhmation of the tetrahydrofuran complex above 250°C. Läppert et al. (1980) prepared the red-brown dimers [(Me3SiC5H4)2YbCl]2 and [(Me3SiC5H4)2YbI]2, and Watson et al. (1981) isolated the compounds Cp2Lu(/x-Cl)2Li and CpjYbdtiQ j L i • (Et 20)2 (see table 9 and fig. 13). A n "open" cyclopentadienyl complex of a rare earth was described recently by Ernst and Cymbaluk (1982). Neodymium trichloride reacts with 2,4-dimethylpentadienyl potassium in tetrahydrofuran with formation of bright green, highly ionic tris(2,4-dimethylpentadienyl) neodymium. The ' H N M R spectrum shows four peaks at 5 = 20.6, 8.5, —1.7, and —29.8 ppm, which are not easily assigned. The X-ray structural analysis (fig. 18, table 11) shows nearly planar 2,4-dimethylpentadienyl ligands, with the carbon atoms in the 2- and 4-positions bent out of the plane i n a direction away from the neodymium atom. A n unsymmetric Charge distribution is postulated in this ligand, having the biggest charge at carbon 3. Two different C - C bond distances are observed, averaging 1.373(12) and 1.421(12) Ä, which supports this resonance hybrid model. A l l known compounds of this section 2.1.2 are shown i n table 8. 2.1.3.

Organometallic

compounds of the rare earths with indenyl, cyclooctatetraenyl

and

other -TT-hgands

Tris(indenyl) complexes of some rare earths were prepared by Tsutsui and Gyshng (1968, 1969) by the reaction of the metal trichlorides with the sodium salt of indene. They are isolated as tetrahydrofuran adducts. The solvent-free tris(indenyl) samarium has been made by the interaction of samarium trichloride with bis(inde-

H. S C H U M A N N and W. G E N T H E

482

nyl) magnesium in benzene (Atwood et al., 1973): RCl3 + 3 N a C , H 7 — ( C , H 7 ) 3 R - ( T H F ) + 3 N a C l ,

(27)

R = La, Sm, G d , Tb, D y , Y b , benzene 2 SmCl3 + 3 Mg(C5H7)2 > 2 (C,H7)3Sm + 3 M g C l ^ .

(28)

The compounds are sensitive to moisture and air. The coordinated tetrahydrofurane can be removed by heating in vacuo to 70°C, and it can be replaced by dioxane and other Lewis bases. The magnetic properties correspond to that of the corresponding cyclopentadienyl complexes (table 12). The proton N M R spectrum of (C9H7)3La in THF-dj, resembles that of the ionic sodium indenide with two low field double doublets at 6 = 7.36 and 6.76 ppm, of relative intensity 2, due to the protons of the benzene ring. A singlet at 8 = 5.48 ppm with a slight shoulder on the low field side with intensity 2 and a triplet with intensity 1 at Ö = 3.19 ppm may be interpreted as an A j X pattern for the five-membered ring. In contrast, the spectrum of the samarium derivative is indicative of an V-indenyl ligand with an A B X pattern of the five-membered ring protons at S = 6.67, 6.25, and 3.18 ppm i n addition to a multiplet for the four benzene ring protons at 6 = 6.98 ppm. The X-ray structure of the solvent-free (C,H7)3Sm (fig. 19), done by Atwood et al. in 1973, shows the samarium atom surrounded by the three five-membered rings of the indenyl ligands in an approximately trigonal planar arrangement of the ring centers around the metal. The crystal data and some bonding distances and angles are given in table 13. Table12 Indenyl complexes of the rare earths. Compound

Color

(C,H7)3Sm (C,H7)3La(THF) (C,H7)3Sm(THF)

red pale tan deep red

(C,H,)3Gd(THF) (C,H,)3Tb(THF) (C,H,)3Dy(THF) (C,H,)3Yb(THF) (C,H7)3Ce-(py) (C,Me,)3Nd(THF)5 (C,Me,)3Er-(THF)3 (C,Me7)2NdCl-(THF) (C5Me7)2ErCl (C5Me7)LaCl2(THF) (C,Me7)NdCl2 (C,Me2)ErCl2-(THF)o.5

pale green pale yellow pale tan dark green yellow

1. 2. 3. 4.

Atwood et al. (1973). Tsutsui and Gysling (1969). Zazzetta and Greco (1979). Tsutsui et al. (1982).

Other data

m.p. 1 8 5 - 2 0 0 ° C , Meffl.55 B.M. Mrff 7.89 B.M. Meff 9.43 B.M. Meff 9.95 B.M. jii,f,4.10 B.M.

Refs. 1 2 2 2 2 2 2 3 4 4 4 4 4 4 4

O R G A N O M E T A L L I C C O M P O U N D S O F T H E R A R E EARTHS

483

Fig. 19. Stereoscopic view of the structure of (C,H7)3Sm (after Atwood et al., 1973).

The structure of tris(indenyl) cerium pyridinate (fig. 20, table 12), which is prepared by the reduction of Ce(0-i-C3H7)4 • (py) by triethyl aluminum (Zazzetta and Greco, 1979), confirms this 77-complexation for the indenyl derivatives. The TT-bonded five-membered portions of the indenyl ligands and the a-bonded nitrogen atom of the pyridine ring are arranged tetrahedrally around the cerium atom. Heptamethylindenyl complexes of lanthanum, neodymium and erbium were synthesized by the reaction of the appropriate rare earth trichloride with potassium heptamethyhndenide in tetrahydrofuran by Tsutsui et al. in 1982. Corresponding to the ratio of the starting materials, the tris(heptamethylindenyl) derivatives of Table 13 Crystallographic data and important bond distances and angles in (C9H7)3Sm and (C9H7)3Ce-(py).

crystal System Space group a(Ä) *(Ä) c(Ä) Z

(C' >' e e V V es d

1 >^

TS " i"

II

-X

=^ i tn VI

(Cp^YCH,)^'» Cp2Y(M-CH3)2Al(CH3)2'' Cp,Y(pi-C,H,),A[(C,H,)^^>

«Cp 5Cp SCp «Cp SCp SCp SCp

5.85s, 6 C H 3 6.12s, 6 C H 3 6.19s, S C H 2 5.95s, S C H 2 6.21s, SCH3 6.18s, S C H 3 6.20s, S C H 2

-0.6s. Spy 8.2, 7.35, 7.25 -0.29s. « A I C H 3 -0.84s -0.58q. 6 C H 3 1.48t, S A l C j H j -O.Olq, 1.15t 3.23s, « N C H 3 1.67s -0.81t.-y(HY) 3.6 -0.32d, 'y(HY) 5, S A I C H 3 -0.98s -0.36m, ^^HY) 4, « C H 3 1.30t. S A I C 2 H 5 -0.19q, l.OU

Cp2YC(CH3)3THF''> Cp2YbC(CH3),THF''

SCp 6.07s, SCH3 1.25s. 6 T H F 3.12m, 0.94m in C^D^ SCp -30.30, SCH3 0.33. 6 T H F 1.39, 0.97 in C^D^

Cp2YbCH2SiMe3THF''

SCp -29.92, S C H 2 0.16. S C H 3 -0.11, S T H F 1.44, 1.02 inC^D^

Cp2LuCH3THF^'

SCp 6.27s, SCH3 -0.62s, S T H F 3.57m, 1.53m in Cf,D^

C P 2 L U C 2 H 5 T H F ^'

SCp 6.17s, S C H j 0.16q, SCH3 1.77t, S T H F 3.41m, 1.41m in toluene-d«

Cp2LuCH(CH3)2THF5>

SCp 6.03s, S C H 0.22sp. SCH3 1.65t, S T H F 3.80m, 1.41m in C(,D^ SCp 6.15s. S C 4 H , 0.15m. 1.27m. S T H F 3.45m. 1.45m in C^D^

Cp2LuC4H,THF*' Cp2LuC(CH3)3THF'' Cp2LuCH2C(CH3)3• T H F ^*

SCp 6.16s, SCH3 1.39s. S T H F 3.32m, 1.13m in C^D^ SCp 6.25s, SCH2 0.27s. 6CH3 1.51s, S T H F 3.21m, 1.17m in C^D^,

Cp2LuCH2SiMe3THF'>

SCp 6.17s, S C H 2 -0.63s, S C H 3 0.55s, S T H F 3.16m, 1.15m in Cf,D^

Cp2LuCH2C(,H5THF*'

SCp 6.17s, S C H j 1.97s, SC^Hj 7.45m, 7.37m, 7.17m, S T H F 3.27m, 1.24m in Cf,D^

C P 2 L U C 6 H 4 - 4 - C H 3 T H F ^' (CH3C5H4)2LuC(CH3)3THF

S.Cp 6.25s, 5 C s H 4 7.93d, 7.39d, 2.78s, S T H F 3.21m, 1.10m in C^D^ SMeCp 5.98, 5.93, 5.78, SCH3CP 2.11, SCH3C 1.34s, S T H F 3.18m, 0.96m

(C5Me5)2LuCH3(C2H,)20^>

SCH3CP

2.18s, S C H 3 L U -0.49s, S C 2 H 5 3.48q, 1.11t, in toluene-dg SCH3CP 2.11s, S C H j 0.53d,y(HH) 8.2, S C H 2.42sp of t, y(HH) 6.59 and 8.8, S C H 3 C H 1.17d, 7(HH) 6.59 in toluene-dg

(C5Me5)2LuCH2CH(CH3)2

S C H 3 C P 1.97s, S C H j 0.17d, y(HH) 8.28, S C H 3 0.82d, / ( H H ) 6.59 in Cf,D,2 " SCp 6.31s, SCH3 -0.77s, S T H F 3.52t, 1.39t in C^D^

Cp2 Lu(M-CH 3) 2 Li • (THF) 2 Cp2 Lu( M-CH 3) 2 Li • (tmed)

SCp 6.26s, SCH3 -0.89s, Stmed 1.84s, 1.57s in C^D^ SCH3CP 1.98s, SCH3 -0.96 in C^D^^

(C5Me5)2LuCH3^' (C,Me5)2LuCH2SiMe3'>

S C H j C p 1.98s, 6 C H 2 -0.39s, S C H 3 -0.03s i n C ^ D , , S C H 3 C P 1.84s, So-C^H; 6.84d (/(HH) 6.45), Sm-C^H, 7.14t,/(HH) 7.6 in C^D,2 S C H 3 C P 1.75s, S C 5 H 4 N 6.89ddd. 7.32td. 7.73dt, 8.2.3dt, 7(HH) 7.36. 5.12, 1.4 in C Holton et al. (1979b). ^' Manzer (1978).

10)

8 C H 3 C P 1.88s, 6 C H 2 - 1.86s, 8 C H 3 -0.11s, S D M E 3.42s, 3.26s in THF-dg

W.J. Evans et al. (1982a). " Schumann et al. (1982).

Watson (1982). ^' Watson and Roe (1982). Schumann et al. (1984b).

Watson (1983a). ""Schumann and Albrecht (1984).

496


Fig. 24. Molecular structure of Cp2Yb(j[i-CH3)2Al(CH3)2 (after Holton et al., 1979b).

are thought to be more ionic. The yellow samarium complex was not isolated free of lithium chloride. Attempts to prepare analogous complexes with In(CH3)3 were without success, as in the case of the preparation of chlorine containing compounds like (C5H5)2Y(,^-Cl)(,u-CH3)A1(CH3)2 or (C,H,)2Y(ii-CH,)2A\iCH,)C\. Single crystal X-ray structural analysis has been carried out for the compounds (C5H5)2R(|ti-CH3)2Al(CH3)2 for R = Y (Scollary, 1978; Holton et al., 1976b) and Y b (Holton et al., 1979b) (fig. 24). The crystallographic data and some important bonding distances and bond angles are given in table 18. The compounds have an approximately tetrahedral environment around both rare earths and the aluminum atom with a R(ju-CH3)2A1 unit as in the dimeric trimethyl aluminum. The yttrium compounds are fluxional at 40°C, but at - 4 0 ° C the bridging and the terminal methyl as well as the ethyl groups give distinct N M R signals (tables 17, 19). Coalescence of these signals in (C5H5)2Y(jii-CH3)2A1(CH3)2 takes place at 40°C. was calculated to be 15.9 k c a l / m o l at 392 K . Both scandium complexes are nonfluxional at room temperature, but their N M R signals collapse to a singlet for the methyl derivative above 100°C. The infrared spectra of the series are nearly identical. They show bands for the bridging methyl groups at 1235 and 1250 c m " ' . The reaction of di-ju-alkyl-bis(cyclopentadienyl) rare earth dialkylaluminum complexes with equimolar amounts of pyridine in toluene at room temperature gives dimeric dicyclopentadienyl rare earth methyl complexes, which are isolated i n about 80% yield as air-sensitive crystalline solids. They are stable for short periods up to 150°C, soluble in CH2CI2, hot toluene or benzene, partly soluble in cold toluene or benzene, but insoluble in saturated hydrocarbons (Holton et al., 1976a and 1979c). The similar reaction of the corresponding scandium derivative with pyridine or tetrahydrofuran does not give the bridging dimer, but a monomer with coordinated pyridine or tetrahydrofuran:

O R G A N O M E T A L L I C COMPOUNDS O F T H E RARE EARTHS

497

Fig. 25. Molecular structure of [(CsHjjjYCHjJj (after Holton et al., 1979c).

CH, ICp^RC

>l(CH,)2 +

2py

CH, CH, toluene

>2(CH3)3Al-py +

^jRCp^,

Cp2R:^

25°C

(39)

CH3

R = Y , Dy. Ho, Er, Tm, Y b , CH3

,

CH3

toluene

2Cp2S
z o > r r o O O

2 •0

Y-C(Cp) Y-Cl(Me) Y-C2(Me) Al-Cl A1-C2 Y-AI

2.62 2.57(2) 2.60(2) 2.08(2) 2.11(2) 3.056(6)

Yb-C(Cp) Yb-Cll Yb-C12 Al-Cll AI-C12 Yb-Al

2.61(3) 2.609(23) 2.562(18) 2.165(22) 2.096(18) 3.014(6)

Y-C(Cp) Y-Cll Y-Cll'

2.655(18) 2.553(10) 2.537(9)

Yb-C(Cp) Yb-Cll Yb-cir

2.613(13) 2.536(17) 2.486(17)

O C

z a O Tl H

X m

angles (deg) Y-Cl-Al Y-C2-A1 C1-Y-C2 C1-A1-C2

81.5(7) 80.1(7) 84.5(6) 112(1)

Yb-Cll-Al Yb-C12-Al C11-A1-C12 C11-A1-C12 Cpl-Yb-Cll Cp2-Yb-Cll

77.7(7) 80.0(6) 87.1(6) 113.3(8) 107.8 104.5

Y-Cll-Y' cii-Y-cir Cpl-Y-Cp2 Cpl-Y-Cll Cpl-Y-Cll'

87.7(3) 92.3(3) 128.9 106.1 110.2

Yb-Cll-Yb' cii-Yb-cir Cpl-Yb-Cp2 Cpl-Yb-Cll Cpi-Yb-cir

86.6(5) 93.4(5) 128.2 105.9 110.0

tn m > H

X

4^

T a b l e 19 N M R spectral data for dicyclopentadienyl rare earth alkyl compounds (S m ppm, / in Hz). Cp^ScCft-CHjjÂlCCHj)^ " Cp2Sc(M-CjH5)jAl(C,H5)2': Cp2Y(M-CH3),AI(CH3)2" Cp2Y(M-C,H,)2Al(C,H,)2'» (Cp^YCHj),^» [(MeCp)2YC4H,]2^' [(MeCp)2YQH„],^' [(MeCrtYCCsHjCHj)]^^' Cp2LuCH(CH3)2(THF) Cp2LuC(CH3)3(THF)'" C p 2 L u C H 2 C ( C H 3 ) 3 ( T H F ) "> Cp2LuCHjSiMe3(THF) CpjLuCH^C^HâHF)'» Cp2LuC6H4-4-CH3(THF)''> (C5 Mcs) 2 LuCH 2 C H ( C H 3) ^5)

SCp 113.2, SCH3 20.7, SAICH3 -6.3

C p 2 L u ( M - C H 3 ) 2 L i ( T H F ) 2 '6) Cp2 Lu( jii-CH 3) 2 Li • (tmed) (C5Me5)2LuCH2SiMe3'' (C5Me5)2LuC,H5^' (C5Me5)2LuC3H4N'> (C5Me5)2LuC,H4Lu(C5Me5)2 7)' (C5Me5)2Lu(/i-CH3)2Li-(tmed)2 ' (C5 Me;) 2 Lu(M-CH3) 2 Li • (DME) 3.5 *

SCp 108.53, SCH3 15.21, S T H F 68.22, 25.38 in Ct,D^

« C p 112.1, S C H j 34.9, S C H , 15.5, S A l C j H , 1.5, 10.4 SCp 112.2, S C H 3 7.86, V ( C Y ) 12.2, S A I C H 3 -7.9 SCp 111.7, S C H 2 20.75. V ( C Y ) 12.2, SCH3 13.0, SAIC2H5 -0.34, 10.4 SCp 111.3, SCH3 23.0, V ( C Y ) 25.0 SCp 109.7, 112.9, 120.2. S C H 2 Y 38.7, '/(CY) 22.8, S C H 3 C P 15.9 S C H 2 Y 39.3. 'y(CY) 23.0 SCp 112.3, 116.6, 121.9, SCH3CP 15.1 SCp 109.6, S C H 36.4, 5CH3 25.4, S T H F 69.7, 25.9 SCp 111.3, SC 38.6, SCH3 36.8, S T H F 73.8, 25.9

V3

SCp 110.8, S C H j 37.7, SC 62.6, SCH3 38.3, S T H F 72.9, 25.9

o

SCp 110.8, S C H 2 28.3, S C H 3 5.9, S T H F 72.6, 26.0 SCp 111.4, S C H 2 48.6. SC^H^ 128.9, 125.7, 118.4, S T H F 73.4, 26.0

X C

2

SCp 111.8, SC6H4 184.2. 142.2, 129.7, 134.3, SCH3 22.6, S T H F 73.1, 25.9 SCp 118.3, S C H j C p 10.9, S C H j 49.3, S C H 29.2, SCH3CH 29.4

ff • S £ ^

SCp 118.54, S C H j C p 11.5, SCH^ 22.96, S C H , 4.8 in C^D^ SCp 118.81, S C H j C p 10.73, SCf,H^ 125.01, 126.94, 135.98, 198.54 in Cf,D,2 SCp 115.88, SCH3CP 10.45, SC5H4N 120.82, 133.43, 133.81, 145.3, 234.26 in C

Cp2RCH2CH=CH2

+ MgClX,

(46)

R = Sc, X = C l ; R = Sm, Ho, Er, X = Br. In connection with investigations on the catalytic activity of organometallic compounds of the rare earths, anionic homoleptic allyl derivatives of Ce, N d , Sm, G d and D y have been prepared according to eq. (47). A l l y l lithium was generated in situ from Sn(C3H5)4 and another lithium alkyl L i L . The compounds, isolated as their dioxane complexes after precipitation from ethereal solution by addition of dioxane, are described as containing fluxional allyl groups from their infrared and ' H N M R spectra (Mazzei, 1979): THF RCI3

+ 4 L i L + Sn(C3H5)4

>

Li[R(C3H5)4] + SnL4 + 3 L i C l ,

R = Ce, N d , Sm, G d , D y .

(47)

A bis(Pentamethylcyclopentadienyl) lutetium allyl and (C5Me5)2LuCH2C M e = C H 2 are found to be among the final products of the decomposition of ( C 5 M e 5 ) 2 L u C H 2 C H M e 2 as shown by Watson and Roe (1982). The " C N M R spectrum of the allyl complex shows S C H 2 at 68 and SCH at 163 ppm, proving a fluxional R.D. Fischer and Bielang (1980a).

Mjff 9.79 B.M.

7) Atwood et al. (1981). 8) John and Tsutsui (1981). •>) Hart et al. (1970). 10 W.J. Evans and Wayda (1980). 11 W.J. Evans et al. (1983c).

9 10 10 10

510

H . S C H U M A N N and W. G E N T H E

tert-butyl complexes Li[R(t-Bu)4] • (THF)4 with an 8-fold molar excess of tertbutylacetylene in tetrahydrofuran at room temperature proceeds according to eq. (53) with formation of the corresponding homoleptic rare earth alkynides (W.J. Evans and Wayda, 1980). The N M R spectrum of the samarium derivative shows the Y and 5 carbons at 27.7 and 32.4 ppm. The a and ß carbons are not observed. Li[R(t-Bu)4] • (THF)4 -I- 4 H C ^ C C M c j THF

-

,

> 4 C 4 H , o +Li^R(C=CCMe3)4] - ( T H F ) ,

(53)

R = Sm, Er, L u . The reaction of (C5Me5)2Sm • (THF)2 in pentane at — 78°C with an excess of diphenylacetylene yields the olefine (C5Me5)2Sm(QH5)C=C(QH5)Sm(C5Me5)2 which probably has a trans configuration (W.J. Evans et al., 1983c), since hydrolysis generates only trans-stilbene. A n intense charge-transfer-like absorption starting at 1050 nm is responsible for the black color of the compound. With tetrahydrofuran the reaction can be readily reversed. The colors, melting points or decomposition points and the magnetic moments of the known allyl and alkynyl derivatives of the rare earths are given in table 22. 2.4. Homoleptic alkyl and aryl derivatives of the rare earths The simplest organometallic derivatives of the rare earths in the oxidation state R^^ are compounds of the general formula R L , . The coordinative unsaturated nature of these compounds causes high reactivity of nucleophilic reagents at the metal center. Therefore a lot of early attempts to prepare such simple homoleptic organometallic compounds of this metals have been unsuccesful. For a long time only indirect evidence for the existence of such derivatives could be found ( F . A . Cotton, 1955). The solution to this problem and the synthesis of homoleptic organometallic compounds of the rare earths was possible only a couple of years ago. A review on homoleptic organometalhc compounds of the rare earths appeared recently (Schumann, 1983). 2.4.1. Neutral homoleptic derivatives Scandium trichloride and yttrium trichloride react with methyl lithium as well as with phenyl lithium yielding air-sensitive products. But only the phenyl derivatives could be isolated and definitely characterized (Hart and Saran, 1968; Hart et al., 1970): THF

RCl, + 3 LiC^H,

> R(C6H5)3 + 3 L i C l ,

(54)

R = Sc, Y . Their reactions with carbon dioxide, benzophenone, and H g C l j , as well as their infrared spectra and their elemental analyses prove the given formula. Both compounds are pyrophoric. They are insoluble in benzene, but soluble i n tetrahydro-

I

511

ORGANOMETALLIC COMPOUNDS OF T H E RARE EARTHS

furan. In vacuo or under nitrogen, they are stable up to 215°C. The reaction of phenyl lithium with L a C l , or with the trichlorides of some lanthanides did not give analogous derivatives. In the case of lanthanum and praseodymium compounds of the type Li[R(QH5)4] have been formed; the other lanthanides have not until recently given reproducible results. A considerable stabilization of homoleptic organometallic compounds of the rare earths can be achieved by the use of bulky alkyl groups, such as neopentyl, C H j S i l C H , ) , , or CH[Si(CH3)3]2. The compounds R [ C H 2 C ( C H 3 ) 3 ] 3 and R[CH2Si(CH3)3]3, with R = Sc and Y , have been isolated from the reaction of the appropriate organohthium reagent with S C C I 3 or Y C I 3 . The compounds were obtained as analytically pure but air-sensitive, colorless crystals from pentane, containing two T H F molecules coordinated to the metal. The N M R data are consistent with a trigonal bipyramidal structure, the T H F ligands occupying the axial Sites. The coordinated tetrahydrofuran could not be removed in vacuo (Läppert and Pearce, 1973). Whereas the c o m p o u n d s Y [ C H ( S i M e 3 ) 2 ] 3 a n d Sc[CH(SiMe2QH4-2-OMe)2]3 could be obtained solvent free (Läppert and Pearce, 1973; Barker and Läppert, 1974). The latter compound is the first example for another possibility to stabilize three-coordinated organometallic compounds of the rare earths. A l k y l ligands or aryl hgands containing built-in chelating groups, like A , A-dimethylamino-o-benzyl or iV, A-dimethylaminomethylphenyl could be used to prepare solvent-free derivatives of Sc, Y , La, N d and E r (Manzer, 1977a, b, 1978). The benzyl scandium complex Sc(CH2C(,H4-2-NMe2)3 was prepared from anhydrous S C C I 3 and three equivalents of LiCH2Cf,H4-2-NMe2 in tetrahydrofuran and isolated as an extremely air-sensitive, pale yellow crystalline solid. The N M R spectrum proves the formulation of the structure with an octahedral arrangement formed by three covalent S c - C a-bonds and three N - S c bonds (table 23). The yttrium, lanthanum and erbium derivatives could be prepared in the same manner, as well as compounds R(C^H4-2-CH2NMe2)3. T A B L E 23 N M R data of homoleptic alkyl derivatives of Sc, Y and Lu. Compound

S in ppm, J in Hz

ScCCHjSiMcjjjCTHFjj Sc(CH2CMe,)v(™F)2

6 C H 2 -0.27, SMe 1.33 S C H j 0.62, SMe 1.37

Sc(CH2C,H4-2-NMe2)3

S C H 2 -1.64,SMe -2.27

Sc[CH(SiMe3)2]3(THF)2 Y(CH2SiMe3)3(THF)2

S C H -0.16, SMeO.69 6 C H 2 O . O 8 , SMe 0.55 S C H 2 - 0 . 3 5 d , V ( Y H ) 2.5, SMe 0.35

Y[CH(SiMe3)2]3 Y(CH2CMe,),(THF)2

S C H -0.53d, -y(YH) 2.5, SMe 0.40 S C H 2 -0.07d, ^J(YH) 2.5, SMe 1.32

Y[CH(SiMe3)2]3(THF)2

S C H -0.43d, V ( Y H ) 2.5, SMe 0.64 S C H j -0.91, SMe 0.28

4

" C N M R : S C H 2 41.80, SMe 4.79

4

Sc(CH 2 SiMcjC^ H 4-2-OMe) 3

Lu(CH2SiMe3)3(THF)2

Ref.

1. Läppert and Pearce (1973). 2. Manzer (1978). 3. Barker and Läppert (1974). 4. Schumann and Müller (1979).

I


512

H 2 C — N

Fig. 29. Configuration of rare earth organometallics containing built-in chelating groups.

with R = Sc, Y , N d , Er, from the appropriate trichlorides and L i Q H 4 - 2 - C H 2 N M e 2 in refluxing tetrahydrofuran as white or pink insoluble compounds, which are pyrophoric (fig. 29). When 2-dimethylamino-5-methylbenzyl lithium, or 5-tert-butyl-2-dimethylaminomethylphenyl lithium are reacted with S c C l j , scandium tris(2-dimethylamino5-methylbenzyl) or scandium tris(5-tert-butyl-2-dimethylaminomethylphenyl) are formed in the same way. Several lanthanide trichlorides react with trimethylsilylmethyl lithium, yielding complexes, in which two or three tetrahydrofuran ligands are bound to the organolanthanide (Atwood et al., 1978; Schumann and Müller, 1978a, 1979). E r C l j and TmCl3 give pink or white air-sensitive complexes R L 3 ( T H F ) 3 , which crystallize from pentane at low temperature. Above —35 to — 25°C one T H F is lost irreversibly, precipitating the dissolvated complexes on recrystallization (Schumann and Müller, 1979). Y b C l 3 and LUCI3 form the corresponding complexes RL3 • (THF)2 (Atwood et al-, 1978; Schumann and Müller, 1979). The N M R data of the lutetium compound are consistent with a trigonal bipyramidal structure with the T H F ligands occupying axial sites (Schumann and Müller, 1979) (table 23). Maintaining a pentane solution of R(CH2SiMe3)3 • (THF)2, with R = Er, L u , at room temperature for several days results in the loss of T H F and tetramethylsilane and precipitate an extremely pyrophoric material. Quantitative experiments showed one Si(CH3)4 is lost from one molecule of the complex, forming polymeric complexes of the formula [R(CH2SiMe3)(CHSiMe3)]„ with a decomposition point between 380 and 390°C (Schumann and Müller, 1979): THF

R C l 3 -I- 3 LiCH2SiMe3

R(CH2SiMe3)3 •(THF)3 -I- 3 L i C l ,

(55)

R = Er, T m , -25°C

R(CH2SiMe3)3(THF)3 R = Er, T m , Y b , L u ,

R(CH2SiMe3)3 • (THF)2 + T H F ,

(56)


513

R(CH2SiMe3)3(THF)2 40°C

[R(CH2SiMe3)(CHSiMe3)] + Si(CH3)4 + 2 T H F .

(57)

R = Er, L u . A similar decomposition is reported for some related derivatives of yttrium and neodymium (Guzman et al., 1979; Dolgoplosk et al., 1980; Vollershtein et al., 1980). Y C I 3 and N d C l 3 react with LiCH2SiMe3, L i C H 2 P h , and L i C H 2 C M e 2 P h to give unusual organometallic compound. The first step is probably the formation of unstable compounds R L 3 which decompose immediately in the reaction medium, yielding carbene type complexes. These are discussed later (see section 5). RCI3 + 3 L i C H j P h ^ R ( C H 2 P h ) 3 + 3 L i C l ,

(58)

R ( C H 2 P h ) 3 ^ [R(CH2Ph)(ChPh)] +

(59)

C6H5CH3,

R= Y, Nd. Carboranyl derivatives of lanthanum, ihulium and ytterbium are formed when the C-mercuro derivatives of methyl- and phenylcarboranes react with the rare earth metals in tetrahydrofuran at 20°C (Suleimanov et al., 1982a), or from the lithium derivatives of methyl- and phenylcarboranes with the rare earth trichlorides in benzene-ether at 20°C (Bregadze et al., 1983) as complexes with T H F . A carboranyl derivative with a thulium-boron bond is also described. The reaction (eq. 62) may proceed via the formation of B - T m - C derivatives, followed by disproportionation. THF

3Hg(C

C )3R • ( T H F ) „ + 3 H g ,

CL)2 + 2 R ^ 2 ( L C ^

(60)

R = L a , T m , L = M e , Ph, « = 1 or 3, RCl3-l-3LiC

THF/benzene

.CL

»(LC

.C)3R • (THF)„-H 3 LiCl,

(61)

R = L a , T m , Y b , L = M e , Ph, « = 1, 2. THF

C,B,oH„HgMe + Tm

> (C2B,oH„ )3Tm • ( T H F ) + H g .

(62)

20°C

A l l known homoleptic rare earth organyls are tabulated in table 24. 2.4.2. Anionic homoleptic derivatives The first homoleptic organometallic compounds of the lanthanides have been prepared by Hart et al. (1970). The reaction of phenyl hthium with LaCl3 or PrCl3 yields products, inflammable in air, which contain lithium. From analysis and infrared spectra, the formulation of Li[R(C(,H5)4] was suggested: RCI3 + 4 L i C ^ H j

THF

> U[RiQH,)^]

+ 3 LiCl,

(63)

R = L a , Pr. Both compounds are soluble in benzene when first obtained from the original tetrahydrofuran solution but, after complete drying in vacuo, they are insoluble in


514

T A B L E 24

Homoleplic alkyl and aryl derivatives of rare earths. Compound

color

other data

ScPhj

yellow colorless colorless white yellow

m.p. 140°C(dec.) m.p. 6 2 - 6 3 ° C m.p. 6 6 - 6 8 ° C

Sc(CH2SiMe,)3(THF)2 Sc(CH2CMe3)3(THF)2 Sc(C(,H4-2-CH,NMe2)3 Sc(CH2C6H4-2-NMe2)3

m.p. 180-182

Li(Et20)J

[R(t-Bu)4]

+ 3

LiCl,

(67)

-78°C

R = Tb, Er, L u , R ( 0 - t - B u ) 3 + 4 Li-t-Bu

pentane/tmed

* Li(tmed)2] [R(t-Bu)4] + 3 L i O - t - B u , (67a)

R = Er, L u . Complexes Li[R(t-Bu)4] ^re starting materials for the synthesis of homoleptic lanthanide acetylide compounds. They react with an excess of 3,3-dimethylbut-l-yne in tetrahydrofuran at room temperature with complete replacement of the tert-butyl ligands and formation of 2-methylpropane in addition to the new lanthanide acetyhdes (W.J. Evans and Wayda, 1980) (see eq. 5 3 ) . "Ate"-complexes [ L i L 2 ] [ R ( C H 2 S i M e , ) 4 ] , with L = tmed, and [ L i L 4 ] [R(CH2SiMe3)4], with L = T H F and E t 2 0 , can be prepared by the action of the neutral homoleptic rare earth complex R(CH2SiMe3)3 • ( T H F ) 2 with LiCH2SiMe3 either in tetrahydrofuran or in tmed, or from the rare earth trichlorides with an excess of LiCH2SiMe3 (Atwood et al., 1978; Schumann and Müller, 1979; Schumann, 1979a): R(CH2SiMe3)3 • ( T H F ) 2 -f- 2 L i C H 2 S i M e 3 - ^ [ L i L 4 ] [ R ( C H 2 S i M e 3 ) 4 ] , (68) R = Y, L = THF, R = Y , Er, Y b , L 2 = tmed, L u C l 3 - ^ 4 L i C H 2 S i M e 3 - — ^ [ L i ( E t 2 0 ) 4 ] [Lu(CH2SiMe3)4], — LiC! Li(Et20)4]

[Lu(CH2SiMe3)4]

+ 2

(69)

tmed

^ [Li(tmed)2] [Lu(CH2SiMe3)4] +4 EtÔ

(70)

The colorless, yellow or pink yttrium, ytterbium or erbium compounds are insoluble in nonpolar solvents but readily soluble i n tetrahydrofuran and ether. W i t h halogenated solvents like C H 2 C I 2 , vigorous reaction occurs. The yttrium tetrahydrofuran complex shows an infrared spectrum with bands for the coordinated T H F shifted to higher frequencies. The ' H and ' ' C N M R spectra i n ether at room temperature are consistent with the given formula, although coupling between yttrium and ' H or ' ^ C was not observed. The C H 2 signal i n the ' ^ C N M R spectrum appears as a weak doublet at — 80°C, suggesting a rapid dissociation-recombination equilibrium at room temperature: [Li(THF)4][Y(CH2SiMe3)4 ^ Y(CH2SiMe3)3(THF)2-l- LiCH2SiMe3(THF),.

(71)

The ether-stabilized lutetium complex shows a different decomposition pathway (Schumann and Müller, 1979). In benzene the compound shows broadening for the

ORGANOMETALLIC COMPOUNDS O F T H E RARE EARTHS

519

C H j resonance in the proton N M R spectrum, which indicates a relatively slow dissociation with respect to the N M R time scale. In a subsequent reaction the complex loses tetramethylsilane by an a-elimination route over a period of one week. A t — 10°C, a white-green compound could be isolated: iLi(Et20)4][Lu(CH2SiMe3)4]

^ S i ( C H 3 ) 4 + 4 EtzO + L i [ L u ( C H 2 S i M e 3 ) 2 ( C H S i M e 3 ) ] .

(72)

Addition of a base like tmed, T H F or D M E , leads to stabiUzed, but benzene-insoluble compounds. The N M R spectrum of [Li(tmed)][Lu(CH2SiMe3)2(CHSiMe3)] in T H F - d g shows only some of the expected signals. A t 6 = 0.02 and - 0 . 0 5 ppm two peaks appear for the trimethylsilyl groups, the signal at - 0 . 0 5 having a half width of 5 H z . The C H j resonance at —1.06 ppm is also broadened to 5 H z ; the C H signal cannot be located with certainty due to its low intensity. Cooling to — 35°C leads to two sharp signals for the trimethylsilyl protons with an approximate integrated ratio of 2 : 1 , suggesting a definite kinetically rather stable compound. Furter loss of one Si(CH3)4 occurs for the complex Li[Lu(CH2SiMe3)2(CHSiMe3)] as revealed by N M R . A t room temperature the spectrum grows a broad unresolved signal centered around 0.40 ppm. After 3 weeks the reaction is complete and the tetramethylsilane concentration remains constant. Careful investigations in the rare earth trichloride trimethylsilylmethyl lithium System revealed the simuhaneous formation of neutral and ionic species, even with an excess of R C l 3. The ionic derivatives decompose by the outlined a-elimination mechanism, finally resulting in an extremely pyrophoric compound with the unusual stoichiometry L i : R = 1: 2. A l l analytical figures are best rationalized by the following formulation: ([Li(THF)2][R2(CH2SiMe3)2(CHSiMe3)(CSiMe3)]}„ (Schumann and Müller, 1978c; Schumann, 1979a). E r C l j and Y b C l 3 react with LiCH(SiMe3)2 containing the even bulkier ligand bis(trimethylsilyl) methyl with formation of moderately soluble complexes with both rare-earth-carbon and rare-earth-chlorine bonds (Atwood et al., 1978): XHF RCI3

+ 3 LiCH(SiMe3)2

> [ L i ( T H F ) 4 ] [R{CH(SiMe3)2}3Cl] -^2 LiCl,(73)

R = Er, Y b . The erbium compound decomposes upon heating in hexane with formation of a pink solution, which contains the lithium salt of the homoleptic anion [Er(CH(SiMe3)2}4] . This complex could not be prepared independently via chlor i d e - s i l y l exchange from [ L i ( T H F ) 4 ] [ E r { C H ( S i M e 3 ) 2 JsCl] and excess LiCH(SiMe3)2. A Single crystal X-ray structural analysis of the ytterbium complex (Atwood et al., 1978) shows a tetrahedral arrangement around ytterbium (fig. 32). The bond lengths Y b - C (2.372, 2.373, 2.391 Ä) and Y b - C l (2.486 Ä) are shorter than in previous know organometallics of the lanthanides. The bond angles around ytterbium give a distorted tetrahedron (table 26). A l l known anionic homoleptic rare earth derivatives are shown in table 27; some N M R data in table 28.


520

Fig, 32. The structure of the anion {Yb(CH(SiMe3)2]3}" (after Atwood et al., 1978).

T A B L E 26

Crystallographic data and important bond distances and bond angles of [U(THF)4][Yb{CH(SiMe3)2}3Cl]. crystal System Space group a(A) b(A) c( Ä) Z

orthorhombic P2,2,2, 12.751(5) 19.280(7) 23.210(8) 4 '

bond distances (A) Yb-C(l) Yb-C(2) Yb-C(3) Yb-Cl

2.373(24) 2.372(16) 2.391(20) 2.486(6)

bond angles (deg) C(l)-Yb-C(2) C(2)-Yb-C(3) C(l)-Yb-C(3) C(2)-Yb-Cl C(l)-Yb-Cl C(l)-Yb-Cl

115.9(7) 107.6(8) 107.1(6) 110.3(5) 104.0(5) 112.0(6)

2.5. Organometallic compounds of the rare earths with ylidic ligands The addition of trimethylmethylenephosphorane to a Suspension of rare earth trichlorides in pentane or hexane results i n the formation of pyrophoric phosphonium salts in quantitative yields. While no dehydrochlorination of these salts was

O R G A N O M E T A L L I C COMPOUNDS OF T H E RARE EARTHS T A B L E 27

Anionic homoleptic alkyl and aryl derivatives of rare earths. Compound

Color

Other data

[Li(tmed)),[ScMeJ [Li(tmed)l3[YMe,] (Li(THF)J[Y(CH2SiMe3)4l [L,(tmed)2][Y(CH2SiMe3)4|

colorless

m.p. 9 4 - 9 8 ° C m.p. 1 2 8 - 1 3 0 ° C m.p. 8 5 - 9 0 ° C

4 1 2

[Li(tmed)]3[LaMeJ

white brown yellow

m.p. 1 2 3 - 1 2 4 ° C m.p. 7 9 - 8 2 ° C dec. 200''C

2 1 3

Li[LaPh4] [Li(tmed)]3[CeMeJ [Li(tmed)]3[PrMeJ LilPrPhJ |Li(lmed)]3lNdMes]

white colorless colorless

green brown

86-89°C 59-62°C

4 1.5

> 200°C 78-83°C

3

dec. dec.

85-88°C

1,5 6

dec. dec. dec.

[Li(tmed)|3[SmMe(^]

blue yellow

Li[Sm(t-Bu)4](THF)4

dark gold

[Li(tmed)]3(GdMe^]

yellow green

dec.

[Li(DME)]3[GdMe6] [Li(tmed)]3[TbMe^]

colorless white

dec. 83-85''C m.p. 114-115''C

[Li(Et,0)4][Tb(t-Bu)4l [Li{lmed)2][Tb(t-Bu)4]

white colorless

|Li(tmed)]3[DyMeJ [Li(DME)]3[DyM z z

o tn Z H

a: tn larger ring

Systems

Lu[(CH2)2PR2]3

Fig. 33. Oligomerization equilibria in the System [Lu{(CH2)2P(t-Bu)2 j , ] « with n =1,2,3,...

+

£ r- £. =r Z

(after Schumann and Reier, 1982a).

^

O

o. 3 g n

n- n-

m


525

Tricyclopentadienyl lutetium reacts with triphenylmethylenephosphorane in tetrahydrofuran with formation of a 1 :1 complex, which precipitates from the solvent in colorless crystals, decomposing above 108°C (Schumann and Reier, 1984b). D i cyclopentadienyl lutetium chloride forms in the same way in toluene an 1 :1 complex with triphenylmethylenephosphorane, which is zwitterionic containing a T ) ' - L U - C bond (Schumann and Reier, 1981): _ Cl C p 2 L u C l - ^ P h 3 P ^ C H 2 - ^ CpjLuc;

(78)

CH2PPh3

The colorless compound, which decomposes at 172°C without melting shows an N M R spectrum at room temperatare with one sharp signal for the cyclopentadienyl protons at 6.1 ppm, and the expected doublet for C H , at 0.92 with a large coupling constant V ( H P ) of 17.5 H z in comparison to the 7.5 H z for the starting ylide. The formation of the L u - C bond causes a decrease of electron density at the ylide carbon, shown by the low field shift in the ' ^ C N M R spectrum to 6 = —4.2 from S = 7.5 of the starting ylide and by the drastically reduced coupling constant V ( C P ) of 28.8 H z in comparison to 99.6 H z in the ylide and 83.7 H z for tetraphenylphosphonium chloride. The non-decoupled ' ' ' C N M R spectrum confirms two protons at the yhde carbon, showing a coupling constant of ' / ( C H ) of 118 H z . (C5H5)2Lu(Cl)CH2P(Cf,H5)3 hydrolyzes with formation of cyclopentadiene, lutetium hydroxide and triphenylmethylphosphonium chloride. It reacts with methyl hthium in toluene at - 7 8 ° C with formation of the methylated derivative, which shows an additional N M R signal at 6 = —0.4 ppm for L u C H j . It decomposes at room temperature with evolution of C H 4 via a carbon-hydrogen activation at the S Position of the initial adduct and formation of a five-membered metallacycle (Schumann and Reier, 1984a, b). The corresponding pentamethylcyclopentadienyl derivative shows the same behavior (Watson, 1983): _ Cl Cp2Lu( -^CHjLi CH2P(QH3)3

Cp2Lu'^

CH3

>Cp,Lu(

(79) CH2P(QH,)3

CH2^ /P(QH3)2.

-CH4

The same metallacycle l,l-diphenyl-3,3-dicyclopentadienyl-l-phospha-3-luteto-indane is also isolated as a product of the reaction of tert-butyl lithium with triphenylmethylenephosphorane and dicyclopentadienyl lutetium chloride in tetrahydrofuran at - 7 8 ° C and as the product of the N a H reduction of (C5H5)2Lu(Cl)CH2P(CjH5)3 in toluene at - 15°C (Schumann and Reier, 1984a, b): /CH2^ Cp2LuCl(THF)-hPh3P=CH2 + t - B u L i ^ C p 2 L u

P(C,H5)2,

\/

(80)


526

H

Cl -l-NaH^CpjLuC

+ NaCl

(81)

CH2PPh3

CH2PPh3

HCp2Lu^

'CH2\ ^P(C,H5)2.

Organometallic compounds of the rare earths such as dicyclopentadienyl rare earth chlorides or dicyclopentadienyl(alkyl) derivatives are stabilized by coordinating donor solvents like tetrahydrofuran, increasing the coordination number of the rare earth metal. These donor solvents can be replaced by yhdes, as shown with the formation of the zwitterionic complex Cp2Lu(Cl)CH2PPh3 (Schumann and Reier, 1981). Dicyclopentadienyl(tert-butyl) lutetium tetrahydrofuranate also reacts at room temperature in toluene with triphenylmethylenephosphorane yielding a colorless solid, which decomposes above 122°C with formation of isobutane. The same exchange reaction is found between Cp2LuCH2SiMe3(THF) and Ph3P=CH2 in toluene at - 7 8 ° C , and Cp2Lu(t-Bu)(THF) and Me3P=CHSiMe3 react in toluene at — 15°C also with exchange of tetrahydrofuran against the yüde (Schuman et al., 1983): Cp2Lu(^

-I- C.HoO,

CH2=PPh3 ^ Cp2LuC^

(82)

CH2PPh3 L = CH2SiMe3, t-Bu. Ylide derivatives of lutetium with high thermal stability are obtained using pentamethylcyclopentadienyl lutetium halides as starting materials (Schumann et al., 1984d): Cl (C5Me5)2LuC;

CH2 ;)Na(Et20)2-t-Lic; ^P(CH3)2 CH, Cl CH,

(C5Me5)2Luc:;

;)P(CH3)2-^ L i C l - t - N a C l ,

(83)

CH, CH, C5Me5Na(THF)-l-LuCl3-H2Li(;

^P(CH3)2 CH2

CH, -P(CH3),

CsMejLu CH,

+ 2 LiCl + NaCl.

(83a)

J2 (C5Me5)2Lu(|U-CH2)2P(CH3)2 crystallizes in the space group P2, with a = 9.406(14), 6 = 15.932(26), c = 8.253(11) Ä, /3 = 106.90° (fig. 33a). Some important

ORGANOMETALLIC COMPOUNDS OF T H E R A R E EARTHS

527

023

(after Schumann et al., 1984d). T A B L E 28a

Important bond distances and angles in (C5Me5)2Lu(n-CH2)2P(CH3)2. bond distances

(Ä)

Lu-Cl

2.360(1)

Lu-cr

2.340(1)

Lu-C(Cp) (av.) P-Cl p-cr P-C2

2.650(1) 1.780(3) 1.780(3) 1.810(3)

P-C2'

1.840(3)

bond angles

(deg.)

0Cpl-Lu-0Cp2

140.0(10) 120.0(10) 110.0(10)

Cl-Lu-Cr C1-P-C2 C2-P-C2'

110.0(10)

bond distances and angles are shown in table 28a. (Schumann et al., 1984d). A l l known ylide derivatives of the rare earths are shown in table 29. 2.6. Organometallic compounds of the rare earths with hydride ligands Organo rare earth hydrides were prepared first independently by three groups in the early 1980s by the hydrogenolysis of dicyclopentadienyl yttrium, erbium and

r

528


T A B L E 29

Ylidic derivatives of rare earths. Compound

Color

Cp2Sc(/i-CH2)2PPh2

pale yelow

La[(;u-CH2)2PMe2]3 LaCCHjPMcjCl),

Other data

Refs.

white

dec. 1 9 5 - 2 0 5 ° C

1 2

white green green blue blue

dec. 155°C dec. 1 8 8 - 1 9 5 ° C

) + E [,C(-

2

dec. 140=C dec. 1 6 0 - 1 8 0 ° C dec. leo^c

2 2

THE

2 2

u,

dec. 1 7 9 - 1 8 0 ° C dec. I S r C

2 2

Gd[(/n-CH2)2PMe2]3 GdCCHjPMcjCl),

white white white white

dec. 180°C dec. 155°C

2 2

Ho[(M-CH2)2PMe2]3 Ho(CH2PMe3Cl)3

white white

dec. 1 9 0 - 2 0 0 ° C

2 2

Er[(M-CH2)2PMe2]3 Er(CH2PMe3Cl)3

pink pink

Lu[(M-CH2)2PMe2l3 Lu(CH2PMe3Cl)3

white

dec. 210°C dec. 140°C

2,6

white

Cp2Lu(n-CH2)2P(t-Bu)2

white

dec. 156°C

Cp2Lu(t-Bu)CH(SiMe3 )PMe3 Cp2Lu(Cl)CH2PPh3

white white

m.p. 132°C, IR, N M R

3 4

Cp2Lu(Me)CH2PPh3

white

dec. 172°C dec. 4 0 ° C

5 7

Lu[(M-CH2)2P(t-Bu)2]3 Cp2Lu(t-Bu)CH2PPh3

white white

dec. 136°C dec. 122°C, IR, N M R

3 4

Cp2Lu(CH2SiMe3)CH2PMe3 Cp3LuCH2PPh3

white colorless colorless

m.p. 103°C, IR, N M R dec. 108°C, IR, N M R

4

Pr[(M-CH2)2PMe2]3 Pr(CH2PMe3Cl)3 Nd[(M-CH2)2PMe2]3 Nd(CH2PMe3Cl)3 Sm[(M-CH2)2PMe2]3 Sm(CH2PMe3Cl)3

Cp2LuCH2PPh2

(C5Me5)2Lu(M-CH2)2PMe2 C5 Me, Lu[( ;ii-CH 2) 2 PMe, ] 2 (C5Me5)2LuCH2PPh2

1. Manzer (1976a). 2. Schumann and Hohmann (1976). 3. Schumann and Reier (1982a). 4. Schumann et al. (1983). 5. Schumann and Reier (1981). 6. Schumann et al. (1984d). 7. Schumann and Reier (1984b). 8. Watson (1983a).

colorless colorless

dec. 180°C dec. 1 9 5 - 2 0 5 ° C dec. 160°C

m.p. 126°C

m.p. 208°C, IR, N M R dec. 152°C, IR, N M R NMR

2 2

2SiN spe

2

7 7

6 6 8

beei

id im 1 KM mo i

P2L 8.'

ORGANOMETALLIC COMPOUNDS OF T H E R A R E EARTHS

529

lutetium alkyl derivatives at atmospheric or high pressure (Schumann and Genthe, 1981; W.J. Evans et al., 1982a; Marks and Ernst, 1982): XHF

1

> - [Cp^LuH • (THF)] „ + L H ,

C p ^ L u L • ( T H F ) + H2

(84)

SOatm. n

L = t-Bu, C H 2 C ( C H 3 ) 3 , CH2SiMe3,

C H 2 Q H 5 ,

toluene r

2 Cp^R-t-Bu (THF) + 2 H ^ R = Y , Er, L u ,

-,

> [ C p ^ R H • ( T H F ) ] ^ + 2 ( C H 3 ) 3 C H , (85)

2 (MeCp)2R-t-Bu • ( T H F ) 4- 2 H , -^^^

[(MeCp),RH-(THF)]2-f-2 (CH3)3CH,

(86)

R = Y , Er, L u , (MeCp)2ErCH2SiMe3]2 + 2 H 2 - ^ ^ ^ [(MeCp)2ErH]2 + 2 SiMe4.

(87)

' H and N M R spectra as well as the I R spectra of the lutetium derivatives with H (eq. 84) have been interpreted for a hydrogen-bridged, oligomeric structure T A B L E 30

Crystallographic data and important bond distances and bond angles of [(MeCp)2YH • (THF)] 2 and [(MeCp)2ErH(THF)l2. [(MeCp)2YH(THF)]2

I(MeCp)2ErH(THF)]2

crystal System space group a{A)

monoclinic P2,/c 8.731(3)

orthorhombic Pnnm

b{Ä)

c(A)

19.772(6) 9.054(3)

ß(deg) Z

98.71(3) 2 (dimer)

10.111(5) 12.152(5) 12.711(5) 2 (dimer)

bond distances (Ä) Y-Y' Y-0Cpl Y-0Cp2 Y-O Y-Hl

3.664(1) 2.397 2.414 2.460(8)

Y-H2

2.17(8) 2.19(8)

Y-Hl-Y' Hl-Y-Hl'

114(3) 66(3)

O-Y-Hl

137 (2)

Hl-Y-0Cpl

112 101

bond angles (deg)

Hl'-Y-0Cpl Hl-Y-0Cp2 Hl'-Y-0Cp2

120 100

E r - E r ' 3.616(5)

530


(Schumann and Genthe, 1981). W.J. Evans et al. (1982a) established a dimeric nature for their products by X-ray crystallography of [(MeCp)2YH • ( T H F ) ] , and the analogous Er complex (table 30, fig. 34), as well as Marks and Ernst (1982) for the solvent-free erbium hydride, by cryoscopic molecular weight determination in benzene. [Cp2LuH • ( T H F ) ] , shows a v(LuH) in the infrared spectrum at 1350 c m " ' ()^(LuD)= 975 c m " ' for the D-derivative) and N M R signals at 5 = 3.61 and 1.77 ppm for T H F , 5.90 ppm for C p and 4.69 ppm for the hydrogen bridge. [CP2YH • ( T H F ) ] , shows 5 H at 2.02 ppm with ' / ( Y H ) = 2 7 H z (W.J. Evans et al., 1982a). [(MeCp)2ErH]2 exhibited »'(ErH) at 1520 and 1180 c m " ' which shifted to 1173 and 840 c m " ' on deuteration (Marks and Ernst, 1982). A colorless lutetium hydride formed in the reaction of dicyclopentadienyl lutetium chloride with sodium hydride in tetrahydrofuran has the composition [Na(THF)5][(Cp3Lu)2H • (THF)2], as proved by X-ray structural analysis (Schumann et al., 1984e). The lutetium derivative [Cp2LuH • (THF)]^ does not react with olefins, but with M c j S i C l with formation of Me3SiH (Schumann and Genthe, 1981). The complexes [(C5H4L)2YH • (THF)]2, with L = H , Me, react with t-buty] isonitrile to form a formimidoyl dimer of the composition [(C5H4L)2Y(HC=NCMe3)]2 (W.J. Evans et al., 1983a). The enediyl complex (C5Me5)2SmC(Ph)=C(Ph)Sm(C5Me5)2, which is formed by the reaction of bis(pentamethylcyclopentadienyl) bis(tetrahydrofurano) samarium

Fig. 34. Molecular structure of [(MeCpjjYH •(THF)]2 (after W.J. Evans et a!., 1982a).


ME4

531

ME 10

Fig. 35. Molecular structure of [(C5 Me,) 2 SmH] j (after W.J. Evans et al., 1983b).

and diphenylacetylene, reacts with hydrogen i n hexane solution to give a solvent-free, orange hydride [(C5Me5)2SmH]2. The thermal stabihty of this compound is limited to one to two days in solution and five to seven days in the solid state. The ' H N M R spectrum shows a broad signal at 5 = 15.61 ppm for the hydride and a singlet at — 0.80 ppm for the methyl groups. The infrared spectrum shows the j'(SmH) at 1140 c m " ' and the j'(SmD) for the analogous deuterium derivative, formed from the hydride by reaction with D2, at 820 c m " ' . The X-ray diffraction (fig. 35, table 31) shows that in contrast to the former described hydrides [(MeCp)2RH • (THF)]2, with R = Y , Er, one of the (C5Me5)2Sm units is rotated with respect to the other with a dihedral angle of 87° (W.J. Evans et al., 1983b). A highly reactive pentamethylcyclopentadienyl lutetium derivative was prepared by the reaction of bis(pentamethylcyclopentadienyl) methyl lutetium with hydrogen at 20°C in hexane (Watson, 1982; Watson and Roe, 1982). The ' H N M R spectrum at — 95°C ( 8 L u H = 9.27 ppm) confirms an asymmetric structure of a dimer containing a bridging and a terminal hydrogen, which shows a rapid monomer-dimer equihbrium with AG° at 25°C for the dissociation to be less than 2 k c a l / m o l . r

T

[(C5Me5)2LuCH3]2

hexane ,

2 ^2-^^

T

[(C5Me5)2LuH]2 -I- 2 C H 4 .

(88)

(C5Me5)2LuH cleaves activated carbon-hydrogen bonds even in compounds like Si(CH3)4 (Watson, 1983a). This hydride as well as the corresponding deuterated


532

T A B L E 31

Crystallographic data and important bond distances and bond angles of [(C5Me5)2SmH]2. crystal System space group a(A) b{A) c(A) ß(deg) Z

monoclinic C2/C 16.532(6) 14.260(4) 16.948(4) 104.26(4) 4 (dimer)

bond distances (A) Sm-Sm

3.905(3)

Sml-0Cpl Sm2-0Cp2

2.478 2.470

bond angles (deg) 0Cpl-Sml-0Cp2 0 Cp2-Sm2- 0 Cp2

130.381 134.469

derivative show an analogous reactive behavior like (C5Me5)2LuCH3 (see in section 2.2.). The i ' ( L u - H ) in the I R spectrum of (C5Me5)2LuH is found at 1345 c m " ' and the r ( L u - D ) in the deuterium derivative at 975 c m " ' (Watson, 1983a). A new class of polymetallic organolanthanide polyhydride complexes was found by W.J. Evans et al. (1982b). Dicyclopentadienyl-tert-butyl erbium tetrahydrofuranate decomposes in toluene i n the presence of lithium chloride within ten hours at room temperature with formation of 2-methylpropane, 2-methylpropene and a pink compound, which shows a broad absorption in the infrared spectrum between 1250 and 1200 cm"^ for the v{EtU). A Single crystal X-ray structural determination of a pink prismatic crystal shows cation-anion pairs with three dicyclopentadienyl

Fig. 36. Molecular structure of the anion [CpjErHJjCl" (after W.J. Evans et al., 1982b).


533

T A B L E 32

Crystallographic data and important bond distances and bond angles of [Li(THF)4][(Cp2ErH)3Cl]. crystal System Space group fl(Ä)

monoclinic P2,/c 10.324(5) 28.132(9)

h{A) c (Ä)

16.773(6) 101.00(4) 4

ß(deg) Z bond distances Erl-Er3

(Ä) 3.926(2) 3.692(1)

Er2-Er3 Erl-Cl

3.684(1) 2.64(1)

Er2-Cl Erl-Hl Er3-Hl

2.735(9)

Er3-H2 Er2-H2 Erl-H3 Er2-H3

1.99 2.54 2.18 2.02

Er3-H3

2.39

Erl-Er2

bond angles Cl-Erl-H3 Hl-Er-H3 Erl-Hl-Er3 Hl-Er3-H3 H2-Er3-H3

2.48 2.33

(deg) 64 75 100 74 71

Er2-H2-Er3 H2-Er2-H3 Cl-Er2-H3 Er2-Cl-Erl

108 76

Erl-H3-Er2 Erl-H3-Er3

139 108

Er2-H3-Er3

113

64 93.9(3)

erbium units, three hydrogens and one chlorine arranged in the anions, providing a formal coordination number of nine for each erbium atom (fig. 36, table 32). Another complex of this type, [Li(THF)3][Cp2LuH)3H] is formed when the reaction product of Cp2LuCl and L i C ( C H 3 ) 3 in ether is allowed to warm up to room temperature and additional stirring is continued for several hours. The 270 M H z N M R spectrum of the white crystalhne powder isolated from T H F shows signals at S = 3.61 and 1.77 ppm for T H F , one singlet at 6 = 5.38 ppm for all C p protons and a quartet at 5 = 1.83 ppm ( / = 7.8 Hz) for the hydrogens (W.J. Evans et al., 1982b). Acetylide hydride complexes of samarium, erbium and ytterbium have been made by the cocondensation reactions of Sm, Er, and Y b metal vapor with 1-hexyne at 77K. Polymeric compounds containing [(BuC=C)2SmH], [(BuC=C)2ErH] and [(BuC^C)3Yb2H] units are isolated and shown to be active catalysts for hydrogenation reactions (W.J. Evans et al., 1981c). Interaction of the dicyclopentadienyl rare earth chlorides of Sm, Er, Y b , and L u and sodium borohydride in tetrahydrofuran yields the borohydride complexes, which are isolated as complexes with one tetrahydrofuran (Marks and Grynkewich, 1976; Schumann et al., 1982): THF

CP2RCI • ( T H F ) + NaBH4

> CP2RBH4 • ( T H F ) + N a C l ,

(89)

R = Sm, Er, Y b , L u . The vibrational spectra of the samarium borohydride and borodeuteride complex suggested a tridentate borohydride or borodeuteride bridge. For the smaller E r and

534


Y b atoms, bidentate bridges are proposed (Marks and Grynkevich, 1976). The lutetium complex shows a 1:1 : 1 : 1 quartet in the ' H N M R spectrum at 5 = 1.07 ppm for B H 4 with / ( B H ) = 84 H z (Schumann et al., 1982). The compound loses the coordinated T H F reversibly upon heating in vacuo or toluene. Complexes of the type [(Me3Si)2C5H3]2RBH4 • ( T H F ) , with R = L a , Pr, N d , and Sm, have been prepared with the tetrahydridoborate as a tridentate ligand, and with R = Y and Y b as well as a tetrahydrofuran-free Sc complex with the B H 4 group as a non-fluxional bidentate ligand. The monoclinic scandium complex ( P 2 / c , a = 11.245(3) Ä, fc= 13.114(3) Ä, c = 10.588(3) Ä, ;ß = 103.31(2)°, Z = 2; fig. 37) confirms the structure showing a scandium-hydrogen bond length of 2.03(4) A (Läppert et al., 1983b).

H(2)

Fig. 37. Molecular structure of [(Me3Si)2C5H3]2Sc(n-H)2BH2 (after Läppert et al., 1983b).


535

T A B L E 33

Organometallic compounds of the rare earths with hydride ligands. Compound

color

[Cp2YH(THF)h [CpÊrH-CTHF)],

white pink

1 1

[Cp^LuHCTHF)]^ [Cp2LuH(THF)]„

colorless colorless

1 2

[(MeCp)2YH(THF)]2 [(MeCp)2ErH]2 [(MeCp)2ErH(THF)]2

colorless

1 3

pink

[(MeCp)2LuH(THF)]2 ((C5Me5)2SmH]2 (C5Me5)2LuH

colorless orange

1 1 ,.,„1.4B.M.

colorless

IR, N M R

{C5Me5)2LuD

other data

IR, N M R

Refs.

4 5,11 11

yellow

6

pink peach

6

Cp2YbBH4(THF)

orange orange

6 6

Cp2LuBH4(THF) |(Me3Si)2C5H3]2ScBH4

colorless white

[(Me3Si)2C5H3]2YBH4(THF) [(Me3 Si) 2C5 H 3 ] 2 LaBH 4 • (THF)

white

Cp2SmBH4{THF) CpjErBH^ Cp2ErBH4(THF) Cp2YbBH4

[(Me3Si)2C5H3]2PrBH4(THF) [(Me3Si) 2C5 H 3 ] 2 NdBH4 • (THF) ((Me3Si)2C5H3]2SmBH4(THF) [(Me3Si)2C5H3]2YbBH4(THF) [Li(THF)4][(Cp2ErH)3CI] [Li(THF)3][(Cp2LuH)3H) [Na(THF), ]|(Cp3 Lu) 2 H • (THF) 2 ] [(BuC^C)2SmH)„ [(BuCsC)2ErH]„ [(BuC^C)3Yb2H]„ 1. W.J. Evans et al. (1982a).

white green blue-violet yellow maroon pink colorless colorless

6

7 m.p. 82-84''C

8

m.p. 1 3 0 - 1 3 2 ° C m.p. 9 3 - 9 5 ° C

8 8

m.p. 1 0 5 - 1 0 7 ° C m.p. 1 1 3 - 1 1 5 ° C m.p. 1 1 5 - 1 1 7 ° C

8 8 8

m.p.T25-128°C

8 9 9

X-ray

10 10

purple 7. Schumann et al. (1982).

2. Schumann and Genthe (1981).

8. Läppert et al. (1983b).

3. Marks and Ernst (1982).

9. W.J. Evans et al. (1982b).

4. W.J. Evans et al. (1983b). 5. Watson and Roe (1982). 6. Marks and Grynkewich (1976).

12 10

10. W.J. Evans et al. (1981c). 11. Watson (1983a). 12. Schumann et al. (1984e).

Some data of the known organometalhc compounds of the rare earths with hydride ligands are given i n table 33. 2.7. Miscellaneous compounds with bonds between a rare earth and an element other than carbon 2.7.1. Compounds with rare earth to main group element bonds Cyclopentadienyl rare earth halides, indenyl rare earth halides and cyclooctatetraenyl rare earth halides are the starting materials for the synthesis of compounds with bonds between the rare earth metals and other elements of the periodic table. They are described as key substances i n sections 2.1.1, 2.1.2, 2.1.3.


536

Dichloro(triphenylmethyl) (2,2,2-cryptate)lanthanum(III), a deep red crystalline solid, was prepared by Campari and Hart (1982) and characterized by its infrared and electronic spectrum: LaClj • N(CH2CH20CH2CH20CH2CH2)3N + L i C P h , THF

> (Ph3C)LaCl2N(CH2CH20CH2CH20CH2CH2),N + LiCl.

(90)

The following carboranyl derivatives of La, Tm, and Y b have been prepared by interaction of the hthium derivatives of carboranes with the appropriate rare earth trichlorides in tetrahydrofuran benzene-ether in 1983 by Bregadze et al.: M e C B , o H i o C L a C l 2 , m.p. 133-135°C, M e C B , o H j o C T m C l 2 - ( T H F ) 4 , m.p. 8 6 - 8 8 ° C , (PhCB,oH,oC)2TmCl • ( T H F ) 5 , m.p. 7 8 - 8 0 ° C , L i [ ( P h C B , o H , o C ) 2 T m C l 2 ] ( T H F ) 5 , m.p. 1 0 6 - 1 0 8 ° C , Li[(MeCB,oHioC)2YbCl2]-(THF)2, m.p. 1 1 3 - 1 1 5 ° C . Dicyclopentadienyl rare earth chlorides react with a variety of compounds containing other anions than C l . Maginn et al. (1963) prepared some methoxides and one phenoxide, Schumann et al. (1982) isolated the dicyclopentadienyl samarium tert-butoxide, and Watson (1982) found bis(pentamethylcyclopentadienyl) lutetium ethoxide as one of the reaction products of the ethanolysis of bis(pentamethylcyclopentadienyl) methyl lutetium. These compounds are much more stable against oxidation. N o X-ray structural determination of these complexes has been done. THF

CP2RCI + N a O L

,

> C P 2 R O L -I- N a C l ,

^

(91)

R = D y , Er, Y b , L = M e , R = Yb, L = P h , R = L u , L = t-Bu. The corresponding reactions of dicyclopentadienyl and di(methylcyclopentadienyl) rare earth chlorides with sodium formiate, sodium acetate, sodium valerate and sodium benzoate yield the carboxylates (Maginn et al., 1963; Coutts and Wailes, 1970; R . D . Fischer and Bielang, 1980a, b). Molecular-weight determinations in boiling benzene indicate these complexes as dimers with ja-carboxylate bridges in this solvent: THF

C P 2 R C L -I- N a 0 2 C l

^

> CP2RO2CL -I- N a C l ,

R = Er, Y b , L = H , R = Sc, Er, Y b , L = M e , R = Y b , L = B u , Ph,

^

(92)


537

2 (MeCp)2RCl + 2 N a O z C C H , CH3

C THF

o

o

(MeCp)2R

R(MeCp)2 -f 2 N a C l ,

(93)

O

O

c CH3

R = G d , Er.

Dicyclopentadienyl scandium chloride reacts with sodium acetylacetonate in benzene with formation of pale yellow C p 2 S c O C ( M e ) C H C ( 0 ) M e , which is monomeric in boiling benzene and subhmes at 1 1 0 ° C / 1 0 ~ ' ' torr (Coutts and Wailes, 1970). The ' H N M R spectrum shows peaks for the C p groups at S = 5.94 ppm, ö C H at 5.06 and S C H j at 1.51 ppm. Tricyclopentadienyl ytterbium reacts with acetylacetone, 2,2,6,6-tetramethyl-3,5-heptadione and 4-anilino-3-pentene-2-one at room temperature in toluene or pentane with liberation of one cyclopentadiene and formation of the dicyclopentadienyl ytterbium derivatives. C p Y b ( C l ) O C ( M e ) C H C ( M e ) N P h was made anaiogously from C p ^ Y b C l ; and C p 2 Y b O C ( M e ) C H C ( M e ) N P h reacts with an excess of the aminoketone with formation of CpYb[OC(Me)CHC(Me)NPh]2 (Bielang and Fischer, 1979): CpjYb + H O C L

C p 2 Y b O C L -I- C p H ,

(94)

H O C L = MeC(0)CH2C(0)Me, t-BuC(0)CH2C(0)-t-Bu, MeC(0)CH2C(Me)NPh. Dicyclopentadienyl tert-butyl lutetium tetrahydrofuranate reacts with carbon monoxide at room temperature in toluene with formation of a pale yellow insertion product, which is air and moisture sensitive and characterized by infrared and N M R spectra [viCO) at 1490 c m " ' , S C H 3 at 0.90 ppm ( ' H ) and 25.25 ppm ( " C ) ] as a 7)^-acyl complex (W.J Evans et al., 1981d): Cp2LuCMe3 • (THF)

C O ^ C P 2 L U - C - C M e 3 ^ C p j L u - C -CMc^.

(95)

This acyl complex reacts with an excess of C O to produce a deep red solution, from which a purple compound can be isolated. This has been shown to contain two lutetium atoms bridged by the enedione diolate ligand 4,5-dihydroxy-2,2,7,7-tetramethyloct-4-ene-3,6-dionato (2), which forms a 6-membered metallocyclic ring with each lutetium atom. Investigations with " C O labelled analogs give evidence for ketene-carbene intermediates during the formation of the final complex, which shows 5CH3 at 1.24 ppm ( ' H ) and 26.89 ppm ( " C ) :

538


Fig. 37a. Molecular structure of (CjMesJjYbSjCNElj (after Tilley et al., 1982c).

CMe, I C =C 2

L u C M c j • ( T H F ) + 4 C O ^ C p , Lu LuCp, C = C'^ I CMcj t CMcj I

-t: —c o^ ^c^c

(96)

V^ L u C p , . o

•3

Bis(pentamethylcyclopentadienyl)carboxylato and -dithiocarbamato derivatives of neodymium and ytterbium have been prepared by Tilley et al. (1982c). The monochnic crystals of the purple (C5Me5)2YbS2CNEt2 (space group C 2 / c , a = 12.268(4) A,b= 15.536(6) Ä,c= 14.269(5) k, ß = 105.23(3)°; Z = 4) show average Y b - C distances of 2.63(3) Ä and an Y b - S distance of 2.70(1) Ä (fig. 37a).


539

Fig. 38. Molecular structure of |Cp2LuOCCMe3CO]2 (after W.J. Evans et al., 1981d).

The results of an X-ray structural analysis are given in fig. 38 and table 34. The reduction of cerium tetra-isopropylate with triethyl aluminum in toluene in he presence of cyclooctatetraene at about 100°C yields cyclooctatetraenyl cerium T A B L E 34

Crystallographic data and important bond distances and bond angles of [(C5H5)2LuOCC(CH3)3CO]2. crystal System

triclinic

Space group fl(A) fe(Ä) C(Ä)

Pl

«(deg) /8(deg) Y (deg) Z

8.284(4) 9.522(4) 10.738(5) 68.01(4) 75.17(4) 80.78(4) 1 (dimer)

bond distances (A) Lu-Ol Lu-02 01-C2 C2-C2' C1-C2' C1-02 L u - 0 Cp

2.09 2.219 1.33 1.40 1.48 1.24 2.60

bond angles (deg) LU-02-C1 02-C1-C2' Cl-C2'-C2

135 122 122

540


di-/i-isopropoxydiethyl aluminum as a yellow crystalline solid containing some toluene which can not be removed in vacuo at room temperature. The compound forms a 1 :1 complex with acetonitrile, when dissolved in this solvent at room temperature and cooled to - 3 0 ° C (Greco et al., 1977): toluene

Cc{0-i-C^Hj)^

• L + 4 A l E t j + CgHg

L = i-C3H70H,

>C8HgCe(M-0-i-C3H7)2AlEt2, (97)

C5H5N.

The known organometallic compounds with bonds between the rare earth metals and oxygen are shown in table 35. The first compound containing a rare-earth-to-nitrogen bond, dicyclopentadienyl erbium amide, is formed when sodium amide is added to a solution of dicycloT A B L E 35

Organometallic compounds of the rare earths containing rare earth to oxygen bonds. Compound

color

CpjDyOCHj CpjErOCH,

yellow

Cp^YbOCHj Cp^YbOC.H,

orange

CpjSmOCCCHj), (C5Me5)2LuOC2H5 CpjErO^CH

pink red colorless pink

other data dec. m.p. m.p. m.p.

orange yellow

CpjYbOjCCHj Cp2Yb02CC4H,

orange yellow

m.p.

CpjYbOjCC^Hj (MeCp)2Gd02CCH3

orange white

m.p.

(MeCp)2Er02CCH3

pink pale yellow

m.p. m.p.

orange

pink

> 235°C

1

236-240°C

1

290-305°C 382-386°C > 50°C

1 1

dec. NMR dec. > 270°C

CpjYbOjCH CP2SCO2CCH3 CpjErOjCCH,

m.p. m.p.

Refs.

282°C (dec.) 331-335°C 325-329°C

2

3,10 1 1 4 1 1 5

m.p.

350-375°C 207-20900

1 1

199-201RCgHg,

(III)

R = Eu, Y b . The cyclooctatetraene ligand is also able to stabilize cerium i n the oxidation state Ce^^. According to eq. (112), dicyclooctatetraene cerium(IV) is reduced by potassium in monoglyme forming an olive green solution, which precipitates as a microcrystalline green complex (Greco et al., 1976): monoglyme

Ce(CgH8)2 + 2 K

-

^

^ [K(monoglyme)]2[Ce(C3H8)2].

(112)

O R G A N O M E T A L L I C COMPOUNDS OF T H E RARE EARTHS

555

Grignard type compounds of some lanthanide metals in the oxidation State + 2 have been investigated by D . F . Evans et al. (1970, 1971). Europium, samarium and ytterbium react in tetrahydrofuran with alkyl and aryl iodides between —20 and -f30°C forming colored Solutions containing mixtures of compounds, which give some Grignard-type reactions. Characterization of the compounds was done only by magnetic susceptibility measurements and some titrimetric analyses. THF

R + LI

>L-R-I,

(113)

R = E u , Sm, Y b , L = M e , Ph, 4-MeC6H4, 2,6-Me2CgH3, 2,4,6-Me3C6H2. A solution of C ^ H j Y b , prepared by the reaction of ytterbium metal and C ^ H j I in tetrahydrofuran reacts with ketones, aldehydes, and nitriles just as Grignard reagents would. However, with esters the complex reacts to produce ketones as the main product (Fukagawa et al., 1981). With benzoyl chloride the ketone is obtained selectively in modest yields which is in contrast to the Grignard reaction (Fukagawa et al., 1982). Europium and ytterbium metal react with propyne i n liquid ammonia at — 78°C with evolution of hydrogen. But only europium(II) propynide could be isolated and characterized (Murphy and Toogood, 1971). Eu + 2 C H 3 C S C H ' " ' ^ " > E u ( C s C C H 3 ) 2 + H 2 .

(114)

Bis(phenylethynyl) ytterbium is available by the reaction of ytterbium metal with bis(phenylethynyl) mercury in tetrahydrofuran, or from the ligand exchange reaction between bis(pentafluorophenyl) ytterbium and phenylacetylene in the same solvent (Deacon and Koplick, 1978): THF

Y b - f Hg(C=CPh)2-

» Yb(C=CPh)2 + H g ,

Yb(Cf,F5)2 + 2 H C s C P h ^ ^ Y b ( C s C P h ) 2 + 2 C^HF,.

(115) (116)

The air-sensitive compound was isolated without any coordinating ligands in addition to the alkyne, but an associated structure is supposed. It reacts with aldehydes L C H O and ketones L 2 C O followed by hydrolysis with formation of alcohols ( P h C = C ) L C H O H or ( P h C = C ) L 2 C O H , but, with benzophenone, reduction to benzopinacol is also found (Deacon and Tuong, 1981). Similar to eq. (115) the complex (t-BuC=C)2R, R = E u or Y b , can be prepared (Deacon et al., 1982b). The hydrolysis of these complexes yields the acetylene as well as a significant amount of alkene and alkane. Bis(pentafluorophenyl) ytterbium is prepared similarly by transmetallation from ytterbium metal and bis(pentafluorophenyl) mercury (Deacon and Vince, 1976; Deacon et al., 1977, 1979). The complex (C6F5)2Yb • ( T H F ) 4 is characterized by infrared, ultraviolet, ' H and ' ^ F N M R spectra. Evidence is presented for green (C(,F5)2Eu (Deacon et al., 1979), and less stable derivatives (CgHF4)2Yb with the

556

H . S C H U M A N N and W. G E N T H E T A B L E 42

Organometallic compounds of the rare earths in the Oxydation State Compound

Color

Othe r data

Cp2Sm-(THF)

purple yellow

Merf

CpjEu Cp^Yb

red green

3.6 B.M.

fetf 7.63 B.M. subl. 4 0 0 - 4 2 0 ° C

CpjYb-CDME)

Refs. 1 2 2 3 4

molecular structure (MeCp)2Yb-(THF)

yellow

(Me3SiC5H4)2Yb

green

(Me3SiC5H4)2Yb-(THF)2

purple

(Me3SiC5H4)2Yb-(tmed)

blue

(C5Me5)2Sm(THF)2 (C5Me5)2Eu(THF)

purple

(C5 Me5) 2 Eu • (THF)(Et 2O)

red red

(C5Me5)2Yb(THF)

red

(C5 Mcs) jYb • (THF)- (C, H 5 C H 3) 1/2 brown-red red (C5Me5)2Yb(THF)2 (C5Me5)2Yb-(Et20) green

m.p. 3 0 8 - 3 1 0 ° C m.p. 120°C m.p. 115°C feff 3.6 B.M. m.p. 1 7 8 - 1 8 1 ° C m.p. 1 8 1 - 1 8 2 ° C , 7.99 B.M. m.p. 2 0 6 - 2 0 9 ° C m.p. 2 0 4 - 2 0 6 ° C dec. 90° C dec. 145°C

(C5Me5)2Yb-(Et20)2 (C5Me5)2Yb(DME) (C5Me5)2Yb-(py)2 CsHgEu CsH^Yb

green

[K(DME)]2[Ce(C8H,)2] C.HjEuI CHiYbl

olive green

m.p.

208-210°C

orange pink

20 5 6 6 6 7 8 8 8 8 9 8 9 9 10 11 11 12 13 13

C2H5YbI

13

C,H5YbI reactivity 4-CH3C^H4YbI

13 22,23 13 13

2,6-(CH3)2C,H3YbI 2,4,6-(CH3)3CsH2YbI (CH3C^C)2Eu

yellow-brown

(C,H5C^C)2Yb

purple dec.

(QF5)2Eu (QF3)2Yb

green

(C,F5)2Yb-(THF)4 (C,HF4)2Yb (C,F4H-2)2Yb

orange

13 14 200°C, N M R , U V

15 24 16 16

reactivity dec. 78°C reactivity

25 17 25 16 16 17

(CH3CB,„H,oC)2Yb(THF)2

dec.

287°C

(C,H3CB,oH,„C)2Yb(THF)2 (C2H2B,„H,)2Yb(THF)

dec. dec.

262°C 290°C

18 18

Cp2Sm(THF)2 Cp2Eu(THF)2

dec. dec.

390-410°C

Cp2Yb(THF)2

dec.

(C5 Me5) 2 Eu • (Me2 PCH 2 PMcj) red (C5 Me5) 2EU • (Me2 PCH 2 C H 2 PMe2) red

m.p. m.p.

(C,F4H-4)2Yb (C,F4H-4)2Yb(THF)4

+.

orange

400-420°C 400-410°C 251-253°C,IR 288-292°C,IR

18 19 19 19 21 21

O R G A N O M E T A L L I C COMPOUNDS O FT H ERARE

EARTHS

557

T A B L E 42 (continued)

Compound

Color

Other data

(C5Mcj) jYb• (Me2PCH2PMe2)

green

m.p. 2"50-253°C, IR, N M R

(C5Me5)2Yb-(Me2PCH2CH2PMe2) (t-C4H,C = C)2Eu (Cf,H5C = C)2Eu-(THF)o25

green

m.p. 2 8 3 - 2 8 5 ° C

brown-orange dec. UV.

Refs.

245-248''C, IR, N M R

(t-C4H5C=C)2Yb C^HsCBioHioCSml C,H5CB,oH,„CEul C.HjCB.oH.oCYbl

iT" 21 24 24 24 26 26 26

1. 2. 3. 4. 5. 6. 7. 8. 9. 10. n.

Watt and Gillow (1969), E.O. Fischer and H. Fischer (1965b). Calderazzo et al. (1966). Deacon et al. (1982). Zinnen et al. (1980). Läppert et al. (1980). W.J. Evans et al. (1981a). Tilley et al. (1980). Watson (1980). Tilley et al. (1982a). Hayes and Thomas (1969a). 12. Greco et al. (1976). 13. D.F. Evans et al. (1971).

14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26.

Murphy and Toogood (1971). Deacon and Koplick (1978). Deacon et al. (1979). Deacon et al. (1977). Suleimanov et al. (1982a). Suleimanov et al. (1982c). Deacon et al. (1983a). Tilley et al. (1983). Fukagawa et al. (1981). Fukagawa et al. (1982). Deacon et al. (1982b). Deacon et al. (1983b). Suleimanov et al. (1983).

hydrogen i n 2- or 4-position are mentioned (Deacon et al., 1977, 1979). A n analogous samarium complex could not be isolated in a pure state. Treatment of trans-Rh(CO)Cl(PPh3)2, N i C l 2 ( b i p y ) , N i C l 2 ( P P h 3 ) 2 and PtCl2(bipy) with ( Q F 5 ) 2 Y b or ( Q H F 4 ) 2 Y b in tetrahydrofuran gives the corresponding polyfluorophenyl organometallics in similar yields with respect to other polyfluorophenyl reagents. Carbonation of (C5F5)2Yb in tetrahydrofuran and acidic quench yields pentafluorobenzoic acid and 2,3,4,5-tetrafluorobenzoic acid, where the hydrogen is derived from tetrahydrofuran (Deacon et al., 1983b). C- and B-ytterbium carboranes have been prepared according to eqs. (117) and (118) from ytterbium metal and C - and B-mercurocarboranes in tetrahydrofuran at room temperature (Suleimanov et al., 1982a): Yb + (o-LCB,oH,oC)2Hg

THF

> (o-LCB,oH,„C)2Yb • ( T H F ) + H g ,

(117)

L = M e , Ph, mYb + ( o - C 2 H 2 B , o H 5 ) 2 H g ^ (o-C2H2BioH5)2Yb • ( T H F ) + H g / Y b , (118) m = 5,6. A Grignard-like intermediate C ^ ^ H j C - B j o H j o - C - R - I ,

has been postulated in the


558

reactions of Q H j C - B j o H i o - C - L i with R I , (R = Sm, Eu, Y b ) and Q H j C - B , o H , o - C - I with R (R = E u , Y b ) , followed by quenching the reaction mixtures with (CH3)3SiCl and CH3C(0)C1 (Suleimanov et al., 1983). The known organometallic compounds of the rare earths in the oxidation State R^^ are shown in table 42.

4. Organometallic compounds of the rare earths in the oxidation state + 4 The best element of the rare earths for the oxidation State + 4 should be cerium, because of the electron configuration of the rare gas xenon for the ion C e " ^ . It is also known from inorganic chemistry, that within the rare earths the lanthanide oxidation state +4 is only stable for Ce""^ in aqueous solution, showing a very strong oxidation strength. The literature of organometallic chemistry contains a few papers dealing with the preparation of some derivatives of Ce'*'^, which are described to have an astonishingly high stability. Tetracyclopentadienyl cerium and tetraindenyl cerium have been prepared as red-orange or yellow solids by interaction of cerium hexachloride dipyridinium complex with sodium cyclopentadienide or sodium indenide, respectively. Both compounds are described as stable against dilute acids and alkalis (Kalsotra et al., 1971a). (C5H(,N)2CeCl6 -I- 4 N a L ^ CeL4 -I- N a C l

2 py • H C l ,

(119)

L = C p , Ind, C , 3 H , . Deacon et al. (1983a) showed that the reaction of sodium cyclopentadienide with dipyridinium hexachlorocerate(IV) in tetrahydrofuran yields only tris(cyclopentadienyl) cerium (III) and not tetrakis(cyclopentadienyl) cerium(IV). The tetrafluorenyl derivative, which is yellow-brown and is stable in dry and inert atmosphere, is prepared in the same manner (Kalsotra et al., 1972c). A n attempt to repeat this synthesis has been reported to be unsuccessful, perhaps due to the low thermal stabihty (Greco et a l , 1976). The di(cyclooctatetraenyl) cerium complex was prepared by the reaction of cerium tetra-iso-propoxide with triethyl aluminum in cyclooctatetraene at 140° C (Greco et al., 1976): C e ( O C H M e 2 ) 4 • M c j C H O H -I- 5 A l E t 3 excess C O T

> CeiC^Hg)^

+ 5 E t j A l O C H M e , -(- C ^ H ^ -h 4 E f .

(120)

The black crystalline compound is pyrophoric, but stable to water. The ' H N M R spectrum consists of a sharp singlet at 5 = 5.6 ppm. The X-ray studies indicate a sandwich type structure as in uranocene. The compound is reduced by potassium to the anion Ce(COT)2~ in essentially quantitative yield, and with an excess of potassium in monoglyme to the Ce^"^ derivative [K(monoglyme)]2[Ce(COT)2]. The preparations of tricyclopentadienyl cerium chloride, bisindenyl cerium dichloride, and dicycloheptatrienyl cerium dichloride are described by the reaction of


559

the cerium hexachloride dipyridinium complex with either sodium cyclopentadienide, sodium indenide, or cycloheptatriene in tetrahydrofuran or benzene, or by redistribution between dipyridinium cerium hexachloride and tetracyclopentadienyl cerium or tetraindenyl cerium (Kalsotra et al., 1971b, d): ( C 5 H 6 N ) 2 C e C l , + 3 N a C p ^ CpjCeCl 4- 3 N a C l + 2py

HCl,

( C 5 H 6 N ) 2 C e C l , + 2 N a l n d ^ I n d ^ C e C l , + 2 N a C l + 2 py • H C l , (C5H6N)2CeCl, + 2 C^Hg ^

( C 7 H 7 ) 2 C e C l 2 + 2 py • H C l + 2 H C l ,

(C5H6N)2CeCl^ -I- 3 Cp4Ce ^ 4 C p j C e C l + 2py (C5H6N)2CeCl(, + Ind^Ce ^

HCl,

(121) (122) (123)

(124)

2 I n d 2 C e C l 2 + 2 py • H C l .

(125)

The brown compounds are described to be stable in water. They should act as starting materials for numerous synthesis yielding tricyclopentadienyl cerium and bisindenyl cerium derivatives of the types C p j C e L and I n d 2 C e L 2 with bonds between the organocerium(IV) moieties and the pseudohalides C N " , N C O ~ , N C S ~ , and Nj" (Kalsotra et al., 1972c), nitro-nitrito, and nitrato groups (Mehra and V i j , 1978), alkoxides (Kapur et al., 1973c), phenols (Kapur et al., 1972), carboxylates (Kalsotra et al., 1971c), and thiols (Kapur et al., 1973a): CpjCeCl-l-ML

THF > CpjCeL-I-MCI,

(126)

THF Ind2CeCl2 + 2 M L

> Ind2CeL2 + 2 MCI,

(127)

M = N a , L = N3, N O 2 , O N O 2 , O 2 C H , O 2 C C H 3 , O 2 C C 2 H 5 , O2CC3H7, SC4H,,

OjCPh, S C H 3 , SC2H5, SC3H7, S C H M c j ,

S-i-C4H,, S-i-CjH,,,

M = K, L = CN, NCO, M = Ag, L = ONO,

NCS, benzene

CpjCeCl + L O H + NEt3

* C p j C e O L -f- E t j N • H C l ,

(128)

L = C H 3 , C 2 H 5 , C 3 H - 7 , {-(Z-^y^j-, C 4 H 9 , i - C ^ H g , i-C^H^], CpjCeCl + L O H ^

CpjCeOL + H C l ,

Ind2CeCl2 + 2 L O H ^

(129)

Ind2Ce(OL)2 + 2 H C l ,

(130)

L = phenol, resorcinol, pyrogallol, phloroglucinol, a-naphthol, yS-naphthol. Even tetrahydroborate derivatives (Kapur et al., 1973b), hydride and amide derivatives (Kapur et al., 1974), as well as some alkyl and aryl derivatives were synthesized. Their infrared spectra have been tabulated (Kalsotra et al., 1973). For all Ce""^ derivatives, further confirmation is necessary. THF

CpjCeCl -H N a L

> Cp3CeL -l- N a C l ,

(131)

Ski'

560

H . S C H U M A N N and W. G E N T H E THF

IndjCeCl, + 2 N a L L=H,

»

Ind2CeL2

+ 2 NaCl,

(132)

BH4,NH2, solvent

CpjCeCl + M L

»CpjCeL + M C l ,

(133)

solvent

Ind,CeCl2 + 2 M L

» Ind2CeL2 + 2 MCI,

M = Mg-halide, L = C H 3 , C 2 H 5 , Ph, M = Li, L =

CH3, C2H5,

Ph,

CH2Ph,

CH2Ph,

(134)

solvent = T H F

solvent = E t 2 O .

5. Other organometallic compounds of the rare earths This section describes recent advances on the synthesis of rare earth organometallic compounds in the -I-1 and 0 oxidation State as well as some compounds which do not significantly belong to one of the earlier described sections. Complexes between some lanthanides in a low oxidation State and olefins were isolated by W.J. Evans et al. (1978a, 1981b). Cocondensation of lanthanum, neodymium, samarium or erbium metal with butadiene or 2,3-dimethylbutadiene at — 196°C in a metal vaporization reactor produces a brown solid, which can be extracted by toluene and tetrahydrofuran yielding soluble brown products with the empirical formulas R(C4Hf,), for R = N d , Sm, Er, and R[(CH3)2C4H4]2 for R = L a , Er. For these complexes the following three formulas have been suggested: C

C ^c-c^ C ~i p ^ C

C

C / C = cc; C D— C

C

c / C = cc; C R ++ c (-)

(A)

(B)

(-)

(C)

of which formula B is the most widely accepted. These complexes are extremely sensitive to both moisture and air. They polymerize immediately on exposure to air. Hydrolytic decomposition produces 2-butenes, 1-butenes and octadienes. The magnetic susceptibility of the complexes differs from those known for lanthanide(III) compounds. La[(CH3)2C4H4]2 is the first known paramagnetic organolanthanum compound (W.J. Evans et al., 1978a). Samarium, erbium and ytterbium metal vapor also react with ethene, propene, and 1,2-propadiene at — 196°C. The colored matrices, orange to black, contain up to 80% of the appropriate metal as shown by the infrared absorptions of the coordinated olefinic double bond. The reaction product of erbium metal and propene was characterized by elemental analysis as E r ( C H 2 = C H C H 3 ) 3 . The predominant volatile products after hydrolysis of the complexes are C H 4 , C2Hg, C 3 H g / C 3 H g and C 4 H s / C 4 H , o for the ethene complexes, C^Û^/C^H^, H 2 C = C = C H 2 , and C H 3 C = C H for the 1,2-propadiene complexes, and C^H^^/C^Hf^, and C H 3 C ^ C H for the propene complexes. Since ethene is only a minor reaction product in the hydrolysis of


561

its complexes with the rare earths, a simple vr-complex structure is not predicted for these complexes. The structure of them is not completely understood (W.J. Evans et al., 1981b). The cocondensation of samarium, erbium, and ytterbium with 3-hexyne at - 1 9 6 ° C forms brown solids, which upon warming up to room temperature and extraction with toluene or tetrahydrofuran give isolable complexes. Complete elemental analyses of these complexes together with molecular weight determinations in benzene indicate the empirical formulas SmCgH,o, Er2C]i,H3Q, and YbCf,H,o. Although a structural characterization has not been performed (W.J. Evans et al., 1979a, b), the complexes are active hydrogenating catalysts (W.J. Evans et al., 1979b). The ytterbium hexyne complex can be used as starting material for new derivatives of ytterbium(III) (Zinnen et al., 1980). Neutral and anionic alkylidene complexes of erbium, thulium, ytterbium and lutetium have been found and investigated by Schumann and Müller (1978c, 1979). The homoleptic species R(CH2SiMe3)3 •(THF)2 of the lanthanides Er, T m , Y b and Lu decompose slowly even at room temperature over several days, generating tetrahydrofuran and tetramethylsilane. The remaining complexes contain CH2SiMe3 and C H S i M e , groups bound to the lanthanide metals. They decompose above 380°C, indicating a polymeric nature of the compounds, consisting of bridging units like [Me3SiCH2R(/i-CHSiMe3)2RCH2SiMe3], but the complete structure has not been solved. Similar structural units containing both carbene and carbyne hgands are proposed to be present in the decomposition products of anionic lutetium alkyl complexes, which have been investigated by Schumann and Müller (1978c, 1979); Li(Et20)4J[Lu(CH2SiMe3)4 Li[Lu(CH2SiMe3)2CHSiMe3] + SiMe^ -I- 4 E t 2 0 ,

(135)

Li[Lu(CH2SiMe3)2CHSiMe3] -I-tmed [Li(tmed)][Lu(CH2SiMe3)CHSiMe3],

(136)

L u C I , + 3 LiCH2SiMe3 THF

> Lu(CH2SiMe3)3 • ( T H F ) 3 + L i C l + SiMe^ + [Li(THF)2] [Lu2(CH2SiMe3)2(CHSiMe3)(CSiMe3)].

(137)

Similar organometallic compounds of the rare earths yttrium and neodymium have been described by Russian scientists (Guzman et al., 1979; Vollershtein et al., 1980; Dolgoplosk et al., 1980). Y C I 3 and NdCl3 react with organohthium compounds, with the formation of complexes which are stable in hydrocarbon Solutions. In analogy to the previously mentioned work of Schumann and Müller (1979), the formation and immediate decomposition of a homoleptic neodymium(III) derivative is discussed in the reaction of NdCl3 with LiCH2SiMe3 (Vollershtein et al., 1980): N d C l j + 3 LiCH2SiMe3

Nd(CH2SiMe3 )3 -I- 3 L i C l ,

2 Nd(CH2SiMe3)3 ^ (Me3SiC=Nd)2CHSiMe3 + 3 SiMe^.

(138) (139)


562

Benzyl lithium reacts with Y C I 3 and N d C l , in diethyiether with evolution of toluene. The following reaction mechanism has been postulated (Guzman et al., 1979; Dolgoplosk et al., 1980): RCI3

+ 3 L i C H j P h ^ R(CH2Ph)3 + 3 L i C l ,

R(CH2Ph)3

(140)

PhCH2-R=CHPh + C ^ H j C H , ,

(I41a)

P h C H 2 - R = C H P h -* polymers with the following units: R Ph-C^

>C-Ph, R"^

-R=C-, I Ph

PhCsR,

(I41b)

R = Y, Nd. The neophyl derivative of yttrium is formed by the same mechanism. The fact that 2 moles of tert-butyl benzene are evolved per yttrium in this reaction indicates the possible formation of a compound containing an yttrium-carbon triple bond (Guzman et al., 1979; Dolgoplosk et al., 1980): Y C I 3 -I-

3 PhCMe2CH2Li ^ Y ^ C C M c j P h

-I-

2 CeHjCMe,

-I-

3 LiCl.

(142)

A vinyl derivative of scandium without having a stabilizing cyclopentadienyl ligand was proposed by Cardin and Norton (1979) according to eq. (143). The C(T)

P

Fig. 47. Line drawing showing the Y b - C interaction in Yb[N(SiMe3)2l2[Me2PCH2CH2PMe2] Tilley et al., 1982b).

(after

T A B L E 43

Other organometalhc compounds of the rare earths Compounds

color

Er(CH2=CHCH3)3 Nd(CH2=CHCH=CH2)3

orange brown

dec. 175°C,

1 2

Sm(CH2=CHCH=CH2)3

brown

M.„ 3.7 B.M. dec. 130°C,

2

other data fi,„ 8.1 B.M.

Ref.

Er(CH2=CHCH=CH2)3

brown

Me,r 2.1 B.M. dec. 100°C, M,,r9.1 B.M.

La(CH 2 =CMeCMe=CH 2) j

brown

dec. 80°,

2

Nd(CH 2 =CMeCMe=CH 2) 2

brown

Er(CH 2=CMeCMe=CH 2) 2 Sm(CH3CH2CsCCH2CH3)

brown

M.errT6 B . M . dec. 190°C Ii,,, 9.4 B . M .

2 2

Er2(CH3CH2CsCCH2CH3)3 Yb(CH3CH2C=CCH2CH3)

brown

[Er(CH2SiMe3)(CHSiMe3)]„

pink white

Li[Lu(CH 2SiMe3) 2CHSiMe3 ] [Li(tmed)]lLu(CH2 SiMe3) 2CHSiMe3 ] YsCC(CH3)2C,H5

3 3 m.p. 385°C

3 4

m.p. 1 1 3 - 1 1 5 ° C

4

4 5 6

(Me3SiCH=Nd)2CHSiMe3 Me2C=CPhScCl 2 • (THF)3 Yb[N(SiMe3)2]2(Me2PCH2)2 (C,H5)3CPrCl2 (C,H5)3CNdCl2 KC,H3)3C]3Nd2Cl3

7 purple

m.p. 1 9 5 - 1 9 7 ° C

W.J. Evans et al. (1981b). W.J. Evans et al. (1978a). W.J. Evans et al. (1979b). Schumann and Müller (1979).

5. Guzman et al. (1979).

8 9 9 9 9

(C^H5)3CGdCl2 (C,H5)3CHoCl2

1. 2. 3. 4.

2

9

6. Vollershtein et al. (1980). 7. Cardin and Norton (1979). 8. Tilley et al. (1982b). 9. Dolgoplosk et al. (1983). 10. Syutkina et al. (1983).

564


complex, which is extremely sensitive to water and other protic reagents shows the olefinic methyl protons at 5 = 1.768 ppm. THF

ScClj + Me3SnCPh=CMe2

> Me2C=CPhScCl2 • ( T H F ) 3 + Me3SnCl.

(143)

Finally it should be stated that an ytterbium-carbon bond is claimed to exist in a phosphine complex of an ytterbium-nitrogen compound via an ytterbium-y-carbon interaction (Tilley et al., 1982b). The X-ray diffraction study of the complex Yb[N(SiMe3)2]2[Me2PCH2CH2PMe2] shows an Y b - C bond distance of 3.04 Ä (fig. 47). This distance is less than the sum of the Van der Waals radius of a methyl group (2.0 A ) , and the divalent metallic radius of ytterbium (1.7 A ) , but longer than the Yb(III)-C^g,^yi distance of 2.57 A in a bridged compound like (Cp2YbMe)2 (Holton et al., 1979a, b). The reaction of triphenylmethyl chloride, benzyl chloride and phenyl bromide with several metallic rare earth elements like N d , Pr, G d and H o in tetrahydrofuran at room temperature has been described but no pure products could be isolated (Dolgoplosk et al., 1983, Markevich et al., 1983, Yakovlev et al., 1983). The structure of the proposed compounds is unclear. In the reaction of 2,2'-dilithium biphenyl with several rare earth tribromides (R = Pr, Sm, G d , Ho, Y b ) the proposed products are metallacycles (Syutkina et al., 1983). A l l y l iodide reacts in situ with cerium amalgam to generate allyl cerium iodide, which in turn reacts with ketones to give homoallylic alcohols to good yields (Imamoto et al., 1981). Organometallic compounds of the rare earths which do not belong to one of the former chapters are listed in table 43.

6. Catalytic application of organometallic compounds of the rare earths The efficiency of a catalytic System based on an organometallic coordination compound depends on the number of metal-atom Orbitals that can be involved in bonding. Therefore derivatives of the reare earths, especially the lanthanides with their partially filled d- and f-orbitals, should provide interesting new opportunities for catalyzing a great variety of organic reactions. A large number of lanthanide oxides, halides, alkoxides and similar compounds show activity as cracking catalysts as well as in oligomerizations, polymerizations and other organic syntheses. Organometallic compounds of the lanthanides are quite likely to be the active species when aluminum alkyls, lithium alkyls or other organometallic compounds are simultaneously present in such reactions. Reviews of these organolanthanide catalysts formed in situ are given by Mazzei (1979) and Marks and Ernst (1982). Imamoto et al. (1982) generated organocerium compounds via the transmetallation reaction of butyl lithium with Cel3. These catalysts react with ketones at — 65°C to form tertiary alcohols in high yields. More extensive research in the near future may inform us about the real nature of the organolanthanide intermediates in such catalytic processes.


565

The first ohgomerization process catalyzed by an isolated organometallic compound of a lanthanide metal was described in 1970 by Gysling and Tsutsui with the trimerization of diphenylacetylene and other derivatives by tricyclopentadienyl samarium. The yttrium aluminum complex Cp2Y(ju-CH3)2 A l M e , (Ballard and Pearce, 1975) and some alkyl-bridged complexes of yttrium and erbium, (Cp2RL)2, [(MeCp)2RL]2 and [(Me3SiC5H4)2RL]2 with L = C H 3 , C^Hg, are active homogeneous ethylene polymerization catalysts (Ballard et al., 1978). Ce(C8Hg)2, Ce2(CgHg)3 and (C8H8)Ce(ju-OCHMe2)2AlEtj are active in Ziegler-Natta catalysts for the ethylene polymerization (Mazzei, 1979). Butadiene can be polymerized to a predominantly 1,4-trans product in yields up to 94% by a System containing L i [ R ( C H = C H C H 3 ) 4 ] • ( d i o x a n e ) / A l B r j or tmed or T H F with R = Ce, N d , Sm, G d , D y (Mazzei, 1979). The reaction of (C5Me5)2LuCH3 with propene, which results in insertion of the olefin into the lutetium-carbon bond, was studied as an experimental model for the coordination catalysis of olefin polymerization by Watson (1982) and Watson and Roe (1982). The kinetics of this insertion reaction, as well as that of the decomposition of the lutetium isobutyl complex formed, are the basis of a general mechanism for the polymerization of ethylene catalyzed by bis(pentamethylcyclopentadienyl) lutetium methyl and for the ;ß-alkyl transfer reaction which is a part of the insertion-deinsertion equilibria. The cocondensation products of lanthanum or erbium metal atoms and 3-hexyne are effective hydrogenation catalysts. 3-Hexyne is hydrogenated to 3-hexene, with a 97% yield of eis product, and a turnover frequency of 0.02 to 0.04 hexyne molecules per metal atom per minute for the erbium compound. 3-Hexene is also hydrogenated (W.J. Evans et al., 1978b, 1979a, b). Alkynide hydrides of samarium, erbium and ytterbium, prepared from metal vapor and neutral unsaturated hydrocarbons, are also able to hydrogenate 3-hexyne to give more than a 96% yield of cis-3-hexene at room temperature and atmospheric pressure (W.J. Evans et al., 1981b, c). Also bis(methylcyclopentadienyl) ytterbium tetrahydrofuranate (Zinnen et al., 1980) and pentamethylcyclopentadienyl samarium hydride derivatives can be used to initiate the catalytic hydrogenation of alkynes like diphenylacetylene or 3-hexyne (W.J. Evans et al., 1983b). Finally it should be noted that organolanthanides like dicyclopentadienyl(tertbutyl) lutetium tetrahydrofuranate activate carbon monoxide to form a new complex with an endiolate ligand (see section 2.7.1.), a reaction which should become quite important in synthetic organic chemistry (W.J. Evans et al., 1981d). A review deahng with his own work in this area appeared recently (W.J. Evans, 1983).

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SUBJECT INDEX

acid ligands 537 activation energy for amorphous-crystalline transitions 291-292, 294 for atomic motion of metal atoms in alloys 291292 for

magnetization reversal 320 acyl compounds 537-538 after effect, magnetic, in amorphous alloys 319, 349-351 alkoxide ligands 536 alkylidine complexes 561 alkyl or aryl ligands 490-505 preparation 496-497, 500-501 structure 497-498, 501503 alkynyl ligands 506 allyl ligands 505-510 amide ligands 540 amorphous alloys crystallization of 295-299 electron paramagnetic resonance (EPR) 382-386 formation of 278-286 hydrogen absorption of 403-407 interatomic distance 304-306 magnetic properties of 313-338 magneto-optical properties of thin films of 351359 miscellaneous properties of 379-407 Mössbauer effect spectroscopy 321-322, 326. 333, 389 nuclear magnetic resonance (NMR) 386-388

photoemission spectroscopy 400-402 preparation of 271-278 stability of 286-299 structure of 299-312 technological applicalions of 407-417 transport properties of 359-379 Ultrasonic measurements 402 anisotropy Parameters in amorphous alloys 319 random, in amorphous alloys 315, 319, 321322, 338, 340, 383 stress induced 341-342, 343 anisotropy field 321-322 antiterromagnetic coupling or interaction between magnetic moments 321-322, 404 asperomagnetic structures 404 asymptotic Curie temperature 317, 421,425 band model for 3d electrons 331, 400-401 band structure caiculation for amorphous alloys 400 for intermetallics 400 bias voltage applied in sputtering 339-340 bisalkynyl compounds 555 biscyclopentadienyl halogeno compounds 453-454 N M R spectra 465-466 structures 458-461 X-ray photoelectron spectra 464 bis(trimethylsilyl)cyclopentadienyl compounds 479-481

573

calorimetric measurements (see specific heat) carborane ligands 513, 536, 557-558 catalytic applicalions 564565 Charge transfer 326, 331, 337, 398 cluster glass 316 clusters of magnetic atoms in amorphous alloys 315, 316 cocondensation, compounds produced by 560 coercive force 319, 328 compensation temperature 322, 426-428, 429-431 compositional short ränge order (CSRO) 309, 332-333 effect on magnetic properties 331-332 compressibility 406 configurational entropy 291292 coupling electron-phonon 37^374, 432-433 indirect R K K Y 314. 317 critical cooling rate 284 critical field in amorphous superconductors 374375 crystal field effects 319, 390 crystallization of amorphous alloys 280-281, 287288, 295-299 crystallization temperature 291-292 crystal structures (see phase equilibria and crystal structures) Curie temperature 347, 421431 cyclopentadienyl dihalo compounds 454 structures 461-462

574

Debye temperature 362, 374, 432-433 density of states 290, 374, 386, 400 dicyclopentadienyl compounds 547-548 with substituted cyclopentadienyl ligands 548-551 diffraction, amorphous alloys neutron 299-300 X-ray 299-300 diffusion of metal atoms 283, 291- 292 distribution of atoms in amorphous alloys 299-300 electric field gradients in amorphous alloys 307 hyperfine fields in amorphous alloys 387, 393-394 domains, magnetic 320 size of 346-347 stabihty of 346-351 electric resistivity in amorphous alloys 359-370 electronegativity 333-334 electron paramagnetic resonance (EPR) in amorphous alloys 382-386 electrons concentration 314, 374 conduction 314, 373-374 Coulomb repulsion 374 spin polarized 313-314, 317 enthalpy of crystallization 290-291 of formation of alloys 292- 293, 294, 332-333 of formation of intermetallic compounds 292293

SUBJECT INDEX and 3d moments 321-322 field interaction between 4f moments 313-314, 321-323 fluctuation in amorphous alloys 334-335 Splitting of 3d band 331-332 extended X-ray absorption fine structure spectroscopy (EXAFS) 306 Faraday effect in amorphous alloys 351-352 Fermi energy 290, 386-387 Fermi wave vector 290, 315, 363-364 ferromagnetic coupling or ordering 314-315 ferromagnetic resonance (FMR) 340, 342, 382 films, amorphous magnetic 338 flash evaporation 277 fluorenyl ligands 484 freezing temperature 315 germyl ligands 542-543 glass formation 279 Grignard type compounds 555

of formation of vacancies or holes 294 entropy configuration in amorphous alloys 291-292 exchange

Hall effect in amorphous alloys 364, 370-373 hardness Al-Ce-Si 6-7 Ce-Co-Si 8-11 Ce-Cu-Si 11-15 C e - N i - S i 29-37 Co-Sc-Si 164-167 C r - S i - Y 218-219 Fe-Sc-Si 168-173 M n - S c - S i 174-176 Ni-Sc-Si 176-180 heat capacity measurements in amorphous alloys 379-380 heat of formation (see enthalpy)

field interaction between 3d moments 321-322 field interaction between 4f

heptamethylindenyl ligands 483-484 homoleptic anionic complexes 513-515

with aryl hgands 513 bis(trimethylsilyl)methyl ligands 519 methyl ligands 515 (t)butyl ligands 516517 trimethylsilylmethyl ligands 518 homoleptic neutral complexes 510-513 with aryl ligands 510 chelating ligands 511 trimethylsilylmethyl ligands 510-511 hybridization of 3d electron States

400

hydride ligands 527-535 hydrogen absorption

in

amorphous alloys 403 hyperfine fields in amorphous alloys 334, 387, 389 hysteresis of magnetization in amorphous alloys 319 indenyl ligands 481-490 interaction Heisenberg 318-319, 336-337 indirect R K K Y 314 interatomic distance in amorphous alloys 304-306 intermetallic compounds 346-347 of rare earths 334-335 of 3d elements 334-335 ionic radii 447 isomer shift in amorphous alloys 397 Kerr effect in amorphous alloys 351-352, 411 ketone ligands 537 kinetic approach to glass formation 382384 to stabihty 291-294 Kissinger method 287-288 Knight shift in amorphous alloys 386 Kondo effect in amorphous alloys 365-367 Kondo scattering of conduction electrons in amorphous alloys 366

SUBJECT INDEX lattice disorder 299-300 ligands acid 537 alkoxide 536 alkyl- or aryl 490-505 preparation 496-497, 500- 501 structure 497-498, 501- 503 alkynyl 506 allyl 505-510 amide 540 carborane 513, 536, 557558 fluorenyl 484 germyl 542-543 heptamethylindenyl 483484 indenyl 481-490 ketone 537 methylcyclopentadienyl 467-481 pentamethylcyclopentadienyl 469-470 phosphicle 541-542 propylcyclopentadienyl (iso) 469 ringbridged cyclopentadienyl 469 stannyl 542-543 substituted cyclopentadienyl 467-481 tetrahydroboranate 533534 triphenylmethyl 535-536 yhdic 520-527 long ränge periodicity suppression by rapid quenching 266-267 magnetic interactions in amorphous alloys between 3d moments 323-324 between 4f and 3d moments 321-322, 323-324 between 4f moments 313-314, 318 magnetic measurements intermetallic compounds 334-335 results in amorphous alloys 313-314, 321-322

magnetic moments of 3d electrons in amorphous alloys 331-334 of 4f electrons in amorphous alloys 318-319 magnetic ordering temperature of amorphous alloys 313, 421 magnetic properties of amorphous alloys 313 magnetic structures of amorphous alloys 315, 321-322 magnetism and/or superconductivity Ag-Ce-Si 4 A g - E u - S i 75 Ag-Nd-Si 139-140 Au-Ce-Si 7-8 A u - D y - S i 48 A u - E r - S i 62 Au-Eu-Pd-Si 252-253 A u - E u - S i 75 A u - G d - S i 85 A u - H o - S i 102 A u - N d - S i 140 A u - P r - S i 155 A u - S i - S m 186 A u - S i - T b 195 A u - S i - Y 216 B - R h - S c - S i 260-261 Ce-Co-Si 8-11 C e - C u - L a - S i 248 C e - C u - M n - S i 246-247 C e - C u - S i 11-15 Ce-Fe-Mn-Si 247-248 C e - F e - S i 17-19 Ce-Ge-Mn-Si 248 Ce-Ir-Si 24 C e - L a - S i 24-25 C e - M n - S i 26-27 Ce-Ni-Si 28-37 Ce-Os-Ru-Si 249 Ce-Os-Si 37 Ce-Pd-Si 37-38 Ce-Pt-Si 39 Ce-Re-Si 39-40 Ce-Rh-Si 40-41 Ce-Ru-Si 41-42 Co-Dy-Si 49-50 C o - E r - S i 62-63 C o - E u - S i 76-77 Co-Fe-Ho-Si 254

575 C o - G d - S i 85-86 Co-Ho-Si 103-104 C o - L a - S i 115-116 C o - L u - S i 133-134 Co-Nd-Si 141-142 Co-Pr-Si 155-156 Co-Sc-Si 164-167 Co-Si-Sm 186-187 C o - S i - T b 195-197 C o - S i - T m 206-207 C o - S i - Y 216-218 C r - M n - N d - S i 259-260 Cu-Dy-Si 50-51 C u - E r - S i 64 C u - E u - S i 77-78 C u - G d - S i 87-88 Cu-Ho-Si 104-105 C u - L a - S i 116-117 Cu-Nd-Si 142-143 C u - P r - S i 156-157 Cu-Si-Sm 187-188 C u - S i - T b 197-198 C u - S i - T m 207 Cu-Si-Y 220 C u - S i - Y b 241-242 D y - F e - H o - S i 249 Dy-Fe-Lu-Si 249-250 D y - F e - S i 51-53 Dy-Fe-Si-Y 250 Dy-Ir-Si 54 D y - M n - S i 54 D y - N d - S i 54-55 Dy-Ni-Si 55-57 D y - O s - S i 57 D y - P d - S i 58 D y - P t - S i 58-59 D y - R e - S i 59 Dy-Rh-Si 59-60 Dy-Ru-Si 60-61 Er-Fe-Ho-Si 251-252 E r - F e - L u - S i 252 E r - F e - S i 64-66 E r - G d - N i - S i 250 Er-Ir-Si 66 E r - M n - S i 66 E r - N i - S i 67-69 E r - O s - S i 69 E r - P d - S i 70-71 Er-Pt-Si 72 E r - R e - S i 72 E r - R h - S i 73-74 E r - R u - S i 74 E u - F e - S i 78

576 magnetism and/or superconductivity {cont'd) E u - L a - P d - S i 253-254 E u - N i - S i 79 Eu-Pd-Si 79-81 Eu-Pt-Si 82 Eu-Rh-Si 82 E u - R u - S i 82 F e - G d - S i 88-92 F e - H o - L u - S i 254-255 Fe-Ho-Si 105-106 F e - H o - S i - Y 255 Fe-La-Si 117-120 Fe-Lu-Sc-Si 256 Fe-Lu-Si 134-135 Fe-Lu-Si-Sm 257 F e - L u - S i - T b 257 F e - L u - S i - T m 257-258 F e - L u - S i - Y 258-259 Fe-Nd-Si 143-145 Fe-Pr-Si 157-158 Fe-Sc-Si 168-173 F e - S c - S i - Y 260 Fe-Si-Sm 188-189 Fe-Si-Tb 198-199 Fe-Si-Tm 207-208 F e - S i - Y 221-223 Fe-Si-Yb 242-243 G d - F e - L u - S i 251 Gd-Ir-Si 94 G d - M n - S i 95 G d - N i - S i 95-98 G d - O s - S i 98 G d - P d - S i 98-99 Gd-Pt-Si 99-100 Gd-Re-Si 100 G d - R h - S i 100-101 G d - R u - S i 102 Ge-Nd-Si 145-146 G e - S i - Y b 243-244 Ho-Ir-Si 106-107 H o - M n - S i 107 Ho-Ni-Si 107-109 Ho-Os-Si 109 Ho-Pd-Si 109-110 Ho-Pt-Si 110 Ho-Re-Si 110 H o - R h - S i 111-112 H o - R u - S i 112 Ir-La-Si 123-124 Ir-Lu-Si 135 Ir-Nd-Si 146 Ir-Sc-Si 173-174

SUBJECT I N D E X Ir-Si-Tb 200 Ir-Si-Tm 208 Ir-Si-Y 225 L a - M n - S i 124-125 L a - M n - S i - Y 255-256 L a - N i - S i 125-128 La-Os-Si 128 La-Pd-Si 128-129 La-Pt-Si 129 La-Re-Si 129-130 L a - R h - S i 131-132 L a - R u - S i 132 L u - M n - S i 135-137 L u - N i - S i 137 L u - O s - S i 137 Lu-Pd-Si 137 Lu-Pt-Si 138 L u - R l i - S i 138 L u - R u - S i 139 M g - S i - Y 226 M n - N d - S i 147-148 M n - P r - S i 159-160 M n - S i - S m 190 M n - S i - T b 200 M n - S i - T m 209-210 M n - S i - Y 226-228 M n - S i - Y b 244-245 M o - S i - Y 228-229 Nd-Ni-Si 148-151 Nd-Os-Si 151 Nd-Pd-Si 151 Nd-Pt-Si 151-152 N d - R e - S i 152-153 Nd-Rh-Si 153-154 N d - R u - S i 154 N i - P r - S i 160-162 Ni-Sc-Si 176-180 N i - S i - S m 190-191 N i - S i - T b 200-202 N i - S i - T m 210 N i - S i - Y 229-235 N i - S i - Y b 245 Os-Pr-Si 162 O s - R h - S c - S i 260 Os-Sc-Si 180 Os-Si-Sm 191-192 Os-Si-Tb 202 O s - S i - T m 210 O s - S i - Y 235 O s - S i - Y b 245 Pd-Pr-Si 163 Pd-Si-Sm 192 Pd-Si-Tb 202-203

Pd-Si-Tm 210-211 P d - S i - Y 235-236 Pd-Si-Yb 245-246 Pr-Pt-Si 163 Pr-Re-Si 163 Pr-Rh-Si 163-164 Pr-Ru-Si 164 Pt-Si-Sm 192 Pt-Si-Tb 203 Pt-Si-Tm 211 Pt-Si-Y 236 Pt-Si-Yb 246 Re-Sc-Si 181-183 Re-Si-Sm 192-193 Re-Si-Tb 203-204 R e - S i - T m 211 Re-Si-Y 236-238 Rh-Sc-Si 183-185 Rh-Si-Sm 193-194 R h - S i - T b 204-205 R h - S i - Y 238-239 R h - S i - Y b 246 Ru-Sc-Si 185 Ru-Si-Sm 194 R u - S i - T b 205 R u - S i - T m 212 R u - S i - Y 240 R u - S i - Y b 246 magneto-optical properties of amorphous alloys 351-359, 408-414 magnetoresistance in amorphous alloys 359-370 magneto-volume effects in amorphous alloys 403 mean field analysis 323, 327, 334-335 mean free path reduction of conduction electrons in amorphous alloys 314 melt extraction 273-274 melt spinning 271-273 metastable character of amorphous alloys 291-292 methylcyclopentadienyl ligands 467-481 adducts with Lewis bases 467 microstructure of amorphous alloys 310-312, 340 Miedema model 281-282, 294, 304-306, 333, 389

SUBJECT I N D E X molecular field model 318319 Mössbauer effect spectroscopy amorphous alloys 321322, 326, 333, 389 neutron diffraction 302-303 neutron scattering 303 nuclear magnetic resonance (NMR) amorphous alloys 386388 nucleation frequency 282-283 nucleation of crystallites in amorphous alloys 282-283 oxidation State II 547-558 III 446 IV 558-560 pair

correlation function in amorphous alloys 302-303, 364-365 pair Potential function in amorphous alloys 364-365 paramagnetic Curie temperature of amorphous alloys 421 Pauli spin susceptibility 386 pentamethylcyclopentadienyl ligands 469-470 halogenbridges to alkali elements 469-470 halogenbridges to another rare earth element 477 halogenbridges to other elements 474-477 phase equilibrium and crystal structures 2 Ag-Ce-Si 4 A g - D y - S i 48 A g - E r - S i 61-62 Ag-Eu-Si 75 A g - G d - S i 83 A g - L a - S i 113 A g - N d - S i 139-140 Ag-Pr-Si 155 Ag-Si-Sm 185-186 A g - S i - Y b 240 A l - C e - S i 4-7

A l - D y - S i 48 A l - E r - S i 61-62 A l - E u - S i 75 A l - G d - S i 83-85 A l - H o - S i 102 A l - L a - S i 113-114 A l - N d - S i 140 A l - P r - S i 155 A l - S i - S m 186 A l - S i - T b 195 A l - S i - T m 206 A l - S i - Y 212-216 A l - S i - Y b 240-241 A u - C e - S i 7-8 A u - D y - S i 48 A u - E r - S i 62 A u - E u - P d - S i 252-253 A u - E u - S i 75 A u - G d - S i 85 A u - H o - S i 102 A u - L a - S i 114-115 A u - N d - S i 140 A u - P r - S i 155 A u - S i - S m 186 A u - S i - T b 195 A u - S i - Y 216 A u - S i - Y b 241 B - R h - S c - S i 260-261 C a - E u - S i 76 C e - C o - S i 8-11 C e - C u - L a - S i 248 C e - C u - M n - S i 246-247 C e - C u - S i 11-15 C e - E u - S i 16 C e - F e - M n - S i 247-248 Ce-Fe-Si 17-19 C e - G a - S i 19-20 C e - G d - S i 20-21 C e - G e - M n - S i 248 C e - G e - S i 21-24 Ce-Ir-Si 24 C e - L a - S i 24-25 C e - M g - S i 25-26 C e - M n - S i 26-27 C e - N d - S i 27-28 C e - N i - S i 28-37 C e - O s - R u - S i 249 Ce-Os-Si 37 Ce-Pd-Si 37-38 Ce-Pr-Si 38 Ce-Pt-Si 39 Ce-Re-Si 39-40 C e - R h - S i 40-41

577 C e - R u - S i 41-42 Ce-Sc-Si 42-44 Ce-Si-Sm 44-45 C e - S i - T h 45-46 C e - S i - U 46 C e - S i - Y 46-48 C o - D y - S i 49-50 C o - E r - S i 62-63 C o - E u - S i 76-77 Co-Fe-Ho-Si 254 C o - G d - S i 85-86 Co-Ho-Si 103-104 C o - L a - S i 115-116 C o - L u - S i 133-134 Co-Nd-Si 141-142 C o - P r - S i 155-156 Co-Sc-Si 164-167 Co-Si-Sm 186-187 C o - S i - T b 195-197 C o - S i - T m 206-207 C o - S i - Y 216-218 C o - S i - Y b 241 C r - G d - S i 86 C r - M n - N d - S i 259-260 Cr-Sc-Si 167 C r - S i - Y 218-219 C u - D y - S i 50-51 C u - E r - S i 64 C u - E u - S i 77-78 C u - G d - S i 87-88 C u - H o - S i 104-105 C u - L a - S i 116-117 C u - L u - S i 134-135 C u - N d - S i 142-143 C u - P r - S i 156-157 Cu-Sc-Si 167-168 Cu-Si-Sm 187-188 C u - S i - T b 197-198 C u - S i - T m 207 C u - S i - Y 220 C u - S i - Y b 241-242 D y - F e - H o - S i 249 D y - F e - L u - S i 249-250, 251 D y - F e - S i 51-53 Dy-Fe-Si-Y 250, 251 D y - G e - S i 53 Dy-Ir-Si 54 D y - M n - S i 54 D y - N d - S i 54-55 D y - N i - S i 55-57 D y - O s - S i 57 D y - P d - S i 58

SUBJECT I N D E X ase equilibrium and crystal structures (cont'd) Dy-Pt-Si 58-59 Dy-Re-Si 59 Dy-Rh-Si 59-60 D y - R u - S i 60-61 E r - F e - H o - S i 251-252 E r - F e - L u - S i 252, 253 Er-Fe-Si 64-66, 263 E r - G d - N i - S i 250, 251 Er-Ir-Si 66 E r - M n - S i 66, 263-264 E r - N i - S i 67-69 Er-Os-Si 69 Er-Pd-Si 70-71 Er-Pt-Si 72 Er-Re-Si 72 E r - R h - S i 73-74 E r - R u - S i 74 E r - S i - Y 74 Eu-Fe-Si 78 E u - G d - S i 78-79 E u - G e - S i 79 E u - L a - P d - S i 253-254 E u - N i - S i 79 Eu-Pd-Si 79-81 Eu-Pt-Si 82 E u - R h - S i 82 E u - R u - S i 82 Eu-Si-Sr 82 F e - G d - L u - S i 254 F e - G d - S i 88-92 F e - H o - L u - S i 254-255 Fe-Ho-Si 105-106 F e - H o - S i - Y 255 Fe-La-Si 117-120 Fe-Lu-Sc-Si 256, 258 F e - L u - S i 134-135 Fe-Lu-Si-Sm 257 F e - L u - S i - T m 257-258 F e - L u - S i - Y 258-259 F e - L u - T b - S i 257 Fe-Nd-Si 143-145 Fe-Pr-Si 157-158 Fe-Sc-Si 168-173 F e - S c - S i - Y 260 Fe-Si-Sm 188-189 Fe-Si-Tb 198-199 Fe-Si-Tm 207-208 F e - S i - Y 221-223 Fe-Si-Yb 242-243 G a - L a - S i 120-121 G d - G e - S i 92-94

G d - I r - S i 94 G d - L a - S i 95 Gd-Mn-S 95 G d - N i - S i 95-98 G d - O s - S i 98 G d - P d - S i 98-99 G d - P r - S i 99 G d - P t - S i 99-100 Gd-Re-Si 100 G d - R h - S i 100-101 G d - R u - S i 102 G e - L a - S i 121-123 Ge-Nd-Si 145-146 Ge-Pr-Si 158-159 Ge-Sc-Si 173 Ge-Si-Sm 189 G e - S i - T b 199 G e - S i - Y 223-225 G e - S i - Y b 243-244 Ho-Ir-Si 106-107 Ho-Mn-S 107 Ho-Ni-Si 107-109 Ho-Os-Si 109 Ho-Pd-Si 109-110 Ho-Pt-Si 110 Ho-Re-Si 110 Ho-Rh-Si 111-112 H o - R u - S i 112 Ir-La-Si 123-124 Ir-Lu-Si 135 Ir-Nd-Si 146 Ir-Sc-Si 173-174 Ir-Si-Tb 200 Ir-Si-Tm 208 Ir-Si-Y 225 L a - M n - S i 124-125 L a - M n - S i - Y 255-256, 257 L a - N i - S i 125-128 L a - O s - S i 128 La-Pd-Si 128-129 La-Pt-Si 129 L a - R e - S i 129-130 L a - R h - S i 131-132 L a - R u - S i 132 La-Sc-Si 133 L a - S i - Y 133 L a - S i - Z r 133 L i - N d - S i 146-147 L i - S i - Y 225-226 L u - M n - S i 135-137 L u - N i - S i 137 L u - O s - S i 137

L u - P d - S i 137 Lu-Pt-Si 138 L u - R e - S i 138 L u - R h - S i 138 L u - R u - S i 139 M g - Y - S i 226 M n - N d - S i 147-148 M n - P r - S i 159-160 Mn-Sc-Si 174-176 M n - S i - S m 190 M n - S i - T b 200 M n - S i - T m 209-210 M n - S i - Y 226-228 M n - S i - Y b 244-245 M o - S i - Y 228-229 Nd-Ni-Si 148-151 Nd-Os-Si 151 N d - P d - S i 151 N d - P t - S i 151-152 N d - R e - S i 152-153 Nd-Rh-Si 153-154 Nd-Ru-Si 154 Nd-Sc-Si 154 N i - P r - S i 160-162 N i - S c - S i 176-180 N i - S i - S m 190-191 N i - S i - T b 200-202 N i - S i - T m 210 N i - S i - Y 229-235 N i - S i - Y b 245 Os-Pr-Si 162 O s - R h - S c - S i 260 Os-Sc-Si 180 Os-Si-Sm 191-192 O s - S i - T b 202 O s - S i - T m 210 O s - S i - Y 235 O s - S i - Y b 245 Pd-Pr-Si 163 Pd-Sc-Si 180 Pd-Si-Sm 192 Pd-Si-Tb 202-203 P d - S i - T m 210-211 P d - S i - Y 235-236 P d - S i - Y b 245-246 Pr-Pt-Si 163 Pr-Re-Si 163 Pr-Rh-Si 163-164 P r - R u - S i 164 Pr-Sc-Si 164 Pt-Sc-Si 180 Pt-Si-Sm 192 Pt-Si-Tb 203

SUBJECT INDEX phase equilibrium and crystal structures {cont'd) Pt-Si-Tm 211 Pt-Si-Y 236 Pt-Si-Yb 246 Re-Sc-Si 181-183 Re-Si-Sm 192-193 Re-Si-Tb 203-204 Re-Si-Tm 211 R e - S i - Y 236-238 Rh-Sc-Si 183-185 Rh-Si-Sm 193-194 Rh-Si-Tb 204-205 R h - S i - Y 238-239 R h - S i - Y b 246 Ru-Sc-Si 185 Ru-Si-Sm 194 Ru-Si-Tb 205 Ru-Si-Tm 212 R u - S i - Y 240 R u - S i - Y b 246 Sc-Si-Sm 185 phase shift 362 phosphicle ligands 541-542 photoemission spectroscopy amorphous alloys 400402 results in intermetallics 400-402 physical properties of amorphous alloys 313, 359-360, 379-380 preparation of amorphous alloys 271-278 pressure effects magnetic properties of amorphous alloys 405 propylcyclopentadienyl(iso) ligands 469 radial

distribution functions 302 resistivity (see electrical resistivity) reviews on amorphous alloys 270 ringbridged cyclopentadienyl ligands 469 R K K Y interaction 314

short ränge order in amorphous alloys 313 specific heat amorphous alloys 374 spin glass 315, 322-323, 334-335 spin waves in amorphous alloys 386 sputtering techniques 277278 stability of amorphous alloys 289, 299-303, 307-308 stannyl ligands 542-543 stress in amorphous alloys 341 structure of amorphous alloys 299-312 substituted cyclopentadienyl ligands 467-481 superconduction in amorphous alloys 373-374 transition temperatures 373-374, 432-433 superconductivity (see magnetism and/or superconductivity) superparamagnetism in amorphous alloys 315 surface effects in amorphous alloys 419-420 technical application of amorphous alloys 407-417 tetrahydroboranate ligands 533-534 thermal conductivity 380 thermodynamic description of formation of amorphous alloys 282-283 thermal stability of amorphous alloys 291-292 thermomagnetic history effects 315-316 thermomagnetic writing 219-292 transition metal amorphous alloys composition and structure 299-300

579 magnetic properties 321, 331 transition metal carbonyl or nitrosyl compounds 544-547 transport properties of amorphous alloys electrical resistivity 359370 Hall effect 370-373 magneto resistance 359370 superconductance 373379 tricyclopentadienyl compounds 448- 467 adducts with Lewis bases 449- 451 mass spectra 466-467 N M R spectra 465 optical absorption spectra 463 preparation 448 properties 449 structures 454-456 vibrational spectra 464465 triphenylmethyl ligands 535536 Ultrasonic measurements amorphous alloys 402 vacancy formation 291-292 valence changes 318 vapour deposition 275-276 viscosity of amorphous alloys 291-292 ylidic

ligands containing 520-527 cyclopentadienyl ligands 523 only ylidic ligands 520523

Ziman-Faber model

362