Tungstotellurates of the organic imidazolium and 4-methyl-imidazolium cations have been prepared and ... Imidazole and 4-methylimidazole have been chosen.
686
Transition Metal Chemistry 24: 686±692, 1999.
Ó 1999 Kluwer Academic Publishers. Printed in the Netherlands.
Tungstotellurates of the imidazolium and 4-methylimidazolium cations Pablo A. Lorenzo-Luis and Pedro Gili* Departamento de QuõÂmica InorgaÂnica, Universidad de La Laguna, E-38200 La Laguna, Tenerife, Canary Islands, Spain Agustõ n SaÂnchez, Departamento de QuõÂmica InorgaÂnica, Facultad de Farmacia, Universidad de Santiago de Compostela, E-15706, Santiago de Compostela, Spain Enrique Rodriguez-CastelloÂn and Jose JimeÂnez-JimeÂnez Departamento de QuõÂmica InorgaÂnica, CristalografõÂa y MineralogõÂa, Facultad de Ciencias, Universidad de MaÂlaga, E-29071 MaÂlaga, Spain Catalina Ruiz-PeÂrez Grupo de Rayos X, Departamento de FõÂsica Fundamental II, Universidad de La Laguna, E-38208, Tenerife, Canary Islands, Spain Xavier Solans Departamento de CristalografõÂa, MineralogõÂa i Deposits Minerals, Universidad de Barcelona, E-08028, Spain Received 13 January 1999; accepted 15 March 1999
Abstract Tungstotellurates of the organic imidazolium and 4-methyl-imidazolium cations have been prepared and characterized by X-ray diffraction and i.r. spectroscopy. The [TeW6O24]6) anion is formed by close packing of oxygen atoms with Te and W atoms in distorted octahedral voids. In both compounds the organic cations are involved in hydrogen bonds, to the [TeW6O24]6) anion in [H2imz]6[TeW6O24] á 2(Himz) (1) and to Te(OH)6 units in [4-H2-methyl-imz]6[TeW6O24] á Te(OH)6 (2). Solution studies of (1) and (2) by 1H-, 183W- and 125Te-n.m.r. have been carried out. Thermogravimetric (t.g.) and calorimetric (d.s.c.) analyses were performed for both compounds. Introduction Polyoxometalates of the Anderson-Evans type [XM6O24]n) (n = 5±8, M = Mo, W) [1] have been reported for a large number of compounds for M = Mo and X = aluminium(III), molybdenum(VI), tellurium (VI), iodine(VII), cobalt(II), copper(II), zinc(II), chromium(III), rhodium(III) and platinium(IV) [2]. Thus, molybdotellurates containing alkaline cations [3±6], transition metals [7±9] and organic cations [2, 10] as counter-ions have been described. However, tungstotellurates are less known [11]. To our knowledge, only Na6[TeW6O24] á 22H2O [12], has been described, although the polyoxotungstates Na2K6[MnW6O24] á 12H2O [13], K5.5K1.5[SbW6O24] á 6H2O [14], K5Na2[SbW6O24] á 12H2O [15], K6Na2[PtW6O24] á 12H2O [16], Na5[H3PtW6O24] á 20H2O [17] and (Na,K)8[NiW6O24] á 12H2O [18] are known. Mixed-type Anderson-Evans [NiIIMo6)xWxO24H6]4) clusters have been reported [1]. * Author for correspondence
On the other hand, studies in solution of tungstotellurates and their thermal behaviour are rare, to our knowledge; only studies by 183W-n.m.r. of the [Ti2W10PO40]7) and [CpFe(CO)2Sn2W10PO38]5) anions have been described [19]. The aim of this work is the preparation of new tungstotellurates with the organic imidazolium and 4methylimidazolium cations and their characterization by X-ray diffraction and i.r. spectroscopy. For the ®rst time in this type of compound, we present the behaviour in solution, using 1H-, 183W- and 125Te-n.m.r. as well as the thermal behaviour using thermogravimetric (t.g.) and calorimetric (d.s.c.) techniques. Imidazole and 4-methylimidazole have been chosen for comparative studies with molybdotellurates of these organic bases previously described [2, 10]. Heteropolytungstates of organic bases can serve as models for the study of the interaction of small organic molecules with a catalic oxide surface such as a tungstotellurate.
687 Experimental General procedures and instrumentation All chemicals were commercially available reagent grade. Deionized water was used for all syntheses. C, H and N analyses were performed with an EA 1108 CHNS-O automatic analyser. I.r. spectra were recorded in the range 4000±250 cm)1 on a Nicolet 710 FTIR spectrophotometer using KBr pellets. The i.r. spectra of dehydrated samples were recorded on the same instrument equipped with an integrating sphere. 1 H-n.m.r. spectra were collected in D2O on a Bruker WP-200 SY spectrometer at 400 MHz with Me4Si as internal standard. 183W-n.m.r. spectra were obtained at 32.59 MHz on a Bruker AMX500 spectrometer at 300 K using a 10 mm Bruker VSP probehead. The 90° pulse was determined as 42.5 ls using a 1M Na2WO4 reference solution in D2O at pH 9 [20]. Saturated, ca. 10)3 M, sample solutions in D2O with a concentric D2O capillary inset for frequency lock were used. All spectra were acquired using a zg30 pulse program, with 1.6 s delay, over a region at ca. 6300 Hz. 125Te-n.m.r. spectra were recorded on the same instrument at 157.91 MHz using the same samples and probe. A saturated solution of K2TeO3 in D2O was used to calculate the 90° pulse as 30 ls. The data were referred to neat Me2Te2 by means of a 0.5 M solution of Ph2Te2 in CH2Cl2 [21] as an indirect external standard (442 ppm). The spectra were acquired using a zg pulse program (15 ls, 45° ¯ip angle), 0.3 s delay and a region of 100 kHz. Chemical shifts are given according to the IUPAC convention. T.g. and calorimetric analyses were performed on a Netzsch STA 409 EP simultaneous thermobalance and a dierential scanning calorimeter, respectively, at dierent heating rates in a dynamic N2 atmosphere of ca. 70 cm3 min)1 in the 22± 650 °C range. The instrument was standarized for temperature and DH against ®ve reference materials, KNO3, In, KClO4, K2SO4 and BaCO3. X.p.s. spectra were recorded on a Physical Electronics 5700 spectrometer equipped with a dual X-ray excitation source (MgKa, hm = 1253.6 eV and AlKa, hm = 1486.6 eV) and an Electronics 80-365B multichannel detector. Preparation of the compounds [H2imz]6[TeW6O24] á 2(Himz) and [4-H2-methyl-imz]6 [TeW6O24] á Te(OH)6 were prepared from a suspension of WO3 (2.9 g, 12.5 mmol), Te(OH)6 (2.3 g, 10 mmol) and imidazole (1.4 g, 20 mmol) for compound (1) and 4-methylimidazole (1.4 g, 17 mmol) for compound (2) in deionized water (1.1 L). The suspensions were heated under re¯ux with stirring for 6 h. The resulting clear solution for both compounds (7.1 £ pH £ 7.5) was reduced ®rst to 300 cm3 by rotatory evaporation and then by slow evaporation at room temperature to 150±100 and 200±150 cm3 for (1) and (2), respectively. Colourless crystals of (1) and (2)
suitable for X-ray analyses were obtained after several weeks. (Found: C, 13.2; H, 1.82; N, 10.3. C24H38W6N16O24Te (1) calcd.: C, 13.3; H, 1.77; N, 10.3%. Found: C, 12.2; H, 1.98; N, 7.1. C24H48W6N12O30Te2 (2) calcd.: C, 12.3; H, 2.07; N, 7.2%). Yields: 85% for compound (1) and 88% for compound (2). Crystal structure determination and re®nement X-ray measurements were performed at 293(2) K using MoKa radiation (k = 0.71069 AÊ, graphite monochromated) on an Enraf-Nonius CAD-4 four-circle diffractometer. Intensity data were obtained by use of an x)2h scan the range 2.31 to 29.97° for compound (1) and 1.53 to 29.99° for compound (2). Cell parameters were obtained from the least-squares re®nement based on 25 re¯ections (6 < h < 18°). Crystal data for the compounds are summarized in Table 5. Atomic scattering factors and anomalous scattering corrections were taken from the literature [22]. The structures were solved by the Patterson and Fourier methods using SHELXS86 [23] and re®ned on F2 using SHELXL93 [24]. Lorentz and polarization, but not absorption, corrections were applied. Software used to prepare molecular graphics and material for publication: ORTEPII [25] and PARST95 [26]. Interatomic distances, positional and anisotropic thermal parameters, bond lengths and angles, best least-square planes and calculated structure factors, have been deposited as supplementary material in the Cambridge Crystallographic Data Centre (CCDC): (1) 103371; (2) 103372. Results and discussion Na6[TeW6O24] á 22H2O [12] was obtained from a heavily modi®ed version of the method of Roy and Mishra [27]. Description of the structures Selected bond lengths and angles are given in Table 1. The structures of compounds (1) and (2) are shown in Figures 1 and 2 respectively. The [TeW6O24]6) anion is formed by close packing of oxygen atoms with Te and W atoms in distorted octahedral voids. In this anion the distorted octahedral TeO6 unit is surrounded by six WO6 groups such that the Te(1)W6 unit is planar [maximum deviation of the atoms from the best least-square plane is 0.0076(3) AÊ] for compound (2). The bond distances are similar to those in the anion of Na6[TeW6O24] á 22H2O [12]. The distortions of the WO6 and TeO6 octahedra have been calculated using the De = 1/ equations [28]: DI = 1/6S[(Ri)R)/R]2, 2 12S[(Di)D)/D] and Da = 1/3S[(ai)180)/180]2, where Ri = an individual WAO or TeAO distances, R = the mean MoAO or TeAO distance, Di = an individual
688 Table 1. Selected interatomic distances (AÊ) and angles (°) for compounds (1) and (2) Compound (1) Te(1)AO(5) Te(1)AO(6a) W(1)AO(1) W(1)AO(2) W(1)AO(3) W(1)AO(4) W(1)AO(5) W(1)AO(6a) W(2)AO(1) W(2)AO(5) W(2)AO(10) N(1)AC(1) N(1)AC(2) a=)x, )y, )z,
1.948(6) 1.932(3) 1.919(6) 1.919(3) 1.720(3) 1.741(6) 2.275(4) 2.282(6) 1.951(4) 2.300(6) 1.728(6) 1.300(5) 1.366(6)
Compound (2) Te(1)AO(5) 1.915(5) Te(1)AO(6) 1.913(5) Te(1)AO(7) 1.936(6) Te(2)AO(13) 1.912(8) Te(2)AO(14) 1.885(8) Te(2)AO(15) 1.855(4) Te(2)AO(16) 1.908(4) Te(2)AO(17) 1.908(6) Te(2)AO(18) 1.929(6) W(1)AO(1) 1.940(8) W(1)AO(2) 1.938(8) W(1)AO(3) 1.740(5) W(1)AO(4) 1.729(5) W(1)AO(5) 2.252(6) W(1)AO(6a) 2.287(4) W(2)AO(1) 1.918(6) W(2)AO(5) 2.303(8) W(2)AO(7) 2.274(5) W(2)AO(8) 1.955(6) W(2)AO(9) 1.735(7) W(2)AO(10) 1.700(5) a=1/2)x, 1/2)y, )z+1
N(2)AC(1) N(2)AC(3) N(3)AC(4) N(3)AC(6) N(4)AC(4) N(5)AC(7) C(2)AC(3) C(8)AC(9) O(5)ATe(1)AO(6) O(4)AW(1)AO(5) O(3)AW(1)AO(5) O(3)AW(1)AO(4) O(1)AW(1)AO(2)
1.340(6) 1.384(7) 1.284(6) 1.323(5) 1.336(5) 1.309(6) 1.316(6) 1.381(4) 94.5(1) 92.9(2) 160.9(2) 105.0(2) 152.6(1)
O(5)AW(2)AO(9) O(1)AW(2)AO(9) O(1)AW(2)AO(5) Te(1)AO(5)AW(1) Te(1)AO(5)AW(2) W(1)AO(1)AW(2) W(1)AO(5)AW(2) C(1)AN(1)AC(2) C(1)AN(2)AC(3) N(1)AC(1)AN(2) N(1)AC(2)AC(3) N(3)AC(6)AC(5) N(5)AC(8)AC(9)
161.2(2) 96.7(2) 73.1(2) 101.8(2) 101.5(2) 117.0(2) 92.3(1) 107.1(4) 107.2(4) 109.9(4) 109.8(4) 109.3(2) 104.0(3)
W(3)AO(2a) W(3)AO(6) W(3)AO(7) W(3)AO(8) W(3)AO(11) W(2)AO(12) O(5)ATe(1)AO(7) O(5)ATe(1)AO(6) O(17)ATe(2)AO(18) O(16)ATe(2)AO(17) O(15)ATe(2)AO(18) O(4)AW(1)AO(5) O(3)AW(1)AO(5) O(3)AW(1)AO(4) O(9)AW(2)AO(10) O(8)AW(2)AO(10) O(5)AW(2)AO(9) O(7)AW(3)AO(12) O(7)AW(3)AO(11) O(6)AW(3)AO(12) Te(1)AO(5)AW(1)
1.912(5) 2.263(6) 2.302(5) 1.907(5) 1.722(6) 1.727(6) 86.2(3) 95.3(2) 51.8(2) 113.6(2) 114.6(2) 94.3(2) 159.8(2) 105.1(3) 105.0(2) 97.8(2) 159.7(2) 92.5(2) 161.3(3) 160.4(2) 103.7(2)
Te(1)AO(5)AW(2) Te(1)AO(6)AW(3) W(1)AO(1)AW(2) W(1)AO(5)AW(2) W(2)AO(7)AW(3) W(2)AO(8)AW(3) N(1)AC(1) N(1)AC(4) N(2)AC(1) N(3)AC(5) N(3)AC(8) N(4)AC(5) N(4)AC(6) C(2)AC(3) C(2)AC(4) C(1)AN(1)AC(4) C(1)AN(2)AC(2) N(1)AC(1)AN(2) N(2)AC(2)AC(4) N(2)AC(2)AC(3) N(3)AC(8)AC(6)
101.6(2) 103.2(2) 116.5(4) 92.1(2) 91.6(1) 116.3(3) 1.353(6) 1.366(8) 1.304(7) 1.303(9) 1.344(8) 1.423(6) 1.318(9) 1.513(7) 1.326(6) 107.1(4) 105.2(4) 111.3(5) 108.9(5) 118.4(4) 102.5(5)
OAO distance, D = the mean OAO distance and ai = an individual OAWAO or OATeAO angle. The values obtained are given in Table 2. Table 2 shows that the compound [H2imz]6[TeW6O24] á 2(Himz) (1) is less distorted than [H2imz]6[TeMo6O24] á 4H2O [10], while the compound [4-H2methyl-imz]6[TeW6O24] á Te(OH)6 (2), exhibits similar distortions to [4-H2-methyl-imz]6[TeMo6O24] á Te(OH)6 [2]. The strengths of the MoAO interactions, s¢ within the WO6 octahedra were calculated from the equation [28] log s¢ = (d1)d)/B, where d is the bond length in AÊ, d1 = 1.9144 AÊ and B = 0.953. In order to calculate the values of the unit charge (u.c.) for the oxygen atoms in the WO6 octahedra, the equation [28] u.c. = s¢)2 was employed. With the u.c. values of the oxygen atoms, it is possible to locate the hydrogen atoms. Thus, those oxygen atoms that present the largest negative values (Table 3), can form hydrogen bonds, as has been found in molybdotellurates of organic cations [2]. In the compounds described here, the organic cations are bonded by hydrogen bonds to the [TeW6O24]6)
anion [compound (1)] and to Te(OH)6 units [compound (2)] where the oxygen atoms do not present a high unit charge (u.c.). For compound (1), hydrogen bonds are observed between the oxygen atoms of the anions and the nitrogen atoms of the imidazolium cations: N
3AH O
3 2:707
4 and N
2AH O
4 2:817
5 AÊ (Figure 1). The molecules of imidazole as solvate, are also hydrogen bonded to the [TeW6O24]6) anion, thus N
5AH O
1 2:696
6 AÊ (x+1/2, )y+1/2+z), in accordance with the relatively high value of the unit charge of these oxygen atoms. This behaviour is dierent to that of the 2-methylimidazolium salt [2-H2methyl-imz]6[TeMo6O24] á 2(2-Hmethyl-imz) [2], where the organic solvate bases are bonded to the organic cations by hydrogen bonds. In (1), the cation and anion possess crystallographicimposed C2 and Cs symmetries. Such symmetries in this cation/anion are unprecedented. The Te(1) atom reside on a center of inversion at the origen. The W(2) and C(7) atoms lie on a crystallographic twofold axis (0, y, 0). The O(2) and O(6) atoms lie on a crystallographic
689
Fig. 1. ORTEP drawing of [H2imz]6[TeW6O24] á 2(Himz) (1). The thermal envelopes enclose a 50% probability. View along the c axis.
mirror plane (x, 0, z) and the C(5)AC(6) bond lie also on the other crystallographic mirror plane (x, 1/2, z) as shown in Figure 1. For compound (2), the Te(2) atom of the Te(OH)6 moiety is on a symmetry axis. The hydrogen bonding interactions are shown in Table 4 and Figure 2. In this compound, as in the 4-methylimidazolium molybdotellurate [4-H2-methyl-imz]6[TeMo6O24] á Te (OH)6 [2], NAH O interactions exist between the oxygen atoms although the values of the u.c. are not highly negative (Table 3), due to the inductive eect of
the methyl group on the nitrogen atom which facilitates the formation of hydrogen bonds. Some relatively short CAH O hydrogen contacts are observed between the oxygen atoms of the anions and the carbon atoms of the cations, as has been found in molybdotellurates of other organic cations [2, 10]. I.r. spectra Interpretation of the i.r. spectra was done by comparison with the literature [2, 9, 10]. Thus, the bands at 890± 950 cm)1 are assigned to masym of cis-WO2 in the [TeW6O24]6) anion. Bands at 670±700 cm)1 can be tentatively assigned to the msym and masym TeAO stretching modes [2, 9, 10], whilst those at 390±995 cm)1 can be tentatively assigned to WAOAW and TeAO [7±9]. In the compounds [H2pyz]6[TeMo6O24] á Te(OH)6 [10], [1-H2methyl-imz]6[TeMo6O24] á Te(OH)6, [4-H2-methyl-imz]6 [TeMo6O24] á Te(OH)6 [2] and [4-H2-methyl-imz]6[TeW6O24] á Te(OH)6 (2), the bands at 3000±3500 cm)1 correspond to the stretching and bending vibrations of the OH groups of the Te(OH)6 [2, 10] solvate. Finally, the bands in the 2861±1993 cm)1 region of both spectra Table 2. Degree of distortion (´104) of WO6 and TeO6 octahedra for compounds (1) and (2)
Fig. 2. ORTEP drawing of [4-H2-methyl-imz]6[TeW6O24] á Te(OH)6 (2). The thermal envelopes enclose a 50% probability.
Atom
(1) Dl
De
Da
(2) Dl
De
Da
Te(1) W(1) W(2) W(3)
0.15 132.4 139.5 132.4
0.01 19.5 27.0 19.5
0.0 151.1 148.3 151.1
0.3 124.1 141.5 138.8
19.7 20.5 18.5 21.1
0.0 161.3 156.7 155.0
690 Table 3. Bond lengths (d/AÊ), bond strengths s¢ of WAO and u.c. values for oxygen atoms in the WO6 polyhedra for compounds (1) and (2) Bond length
d/AÊ
s¢
u.c.
Bond length
d/AÊ
s¢
u.c.
Compound (1) W(1)AO(1) W(1)AO(2) W(1)AO(3) W(1)AO(4) W(1)AO(5) W(1)AO(6) Ss¢
1.919 1.919 1.720 1.741 2.275 2.282
0.989 0.989 1.599 1.633 0.418 0.411 6.039
)1.011 )1.011 )0.401 )0.367 )1.582 )1.589
W(2)AO(1) W(2)AO(5) W(2)AO(10) Ss¢
1.951 2.300 1.728
0.916 0.393 1.569 5.756
)1.084 )1.607 )0.431
1.940 1.938 1.740 1.729 2.252 2.287
0.940 0.944 1.524 1.565 0.442 0.406 5.821 0.991 0.391 0.420 0.906 1.542 1.679 5.929
)1.060 )1.056 )0.476 )0.435 )1.558 )1.593
W(3)AO(2) W(3)AO(6) W(3)AO(7) W(3)AO(8) W(3)AO(11) W(3)AO(12) Ss¢
1.912 2.263 2.302 1.907 1.722 1.727
1.006 0.430 0.393 1.018 1.592 1.572 6.011
)0.994 )1.569 )1.607 )0.982 )0.408 )0.427
Compound (2) W(1)AO(1) W(1)AO(2) W(1)AO(3) W(1)AO(4) W(1)AO(5) W(1)AO(6) Ss¢ W(2)AO(1) W(2)AO(5) W(2)AO(7) W(2)AO(8) W(2)AO(9) W(2)AO(10) Ss¢
1.918 2.303 2.274 1.955 1.735 1.700
)1.009 )1.609 )1.580 )1.094 )0.457 )0.321
Table 4. Hydrogen-bonding distances (AÊ) for compound (2)a Interaction
Symmetry
Distance (AÊ)
cation±anion N(2)ááááO(3) N(4)ááááO(12) N(6)ááááO(9)
+x)1/2,+y)1/2,+z )x+1,+y, )z+3/2 )x+1,+y, )z+1/2
2.748(7) 2.759(7) 2.722(9)
cation±Te(OH)6 C(1)ááááO(13) C(1)ááááO(18) C(5)ááááO(15) C(9)ááááO(15) C(9)ááááO(17)
+x)1/2,+y)1/2,+z )x+1/2,+y)1/2, )z+3/2 )x+1,+y, )z+3/2 )x+1,+y, )z+1/2 +x,+y,+z)1
3.053(0) 3.253(8) 3.060(0) 3.003(9) 3.002(7)
pound (1) and )116.9(30) ppm for compound (2) (w1/2 in Hz are give in parentheses). These results are consistent with the six tungsten atoms in the [TeW6O24]6) kernel being magnetically equivalent. The
Scheme 1. Imidazolium cation, and 4-methylimidazolium cation.
are attributed to m
NAH of the imidazolium cation [2, 10]. N.m.r. studies The 1H- n.m.r. spectrum of [H2imz]6[TeW6O24] á 2(Himz) (1) shows two singlets at 7.18 ppm corresponding to the Ha and Hb protons, and another singlet at 8.19 ppm assigned to the Hc proton [Scheme 1(a)]. These data are as expected for the imidazolium cation [10]. The spectrum of [4-H2-methyl-imz]6[TeW6O24] á Te(OH)6 (2) shows a singlet at d 6.99 ppm corresponding to aH and another singlet at d 8.39 ppm corresponding to b H, while the methyl resonance of the 4-methyl-imidazolium cation [2] [Scheme 1(b)] is observed at d 2.17 ppm. The signal corresponding to the dH proton could not be observed because of exchange between dH and D2O. The 183W-n.m.r. spectra of compounds (1) and (2) in D2O show only one signal, at )115.85(56) for com-
125
Te-n.m.r. spectra of the compounds, show one signal at 833.65(37) for (1) and 833.59 ppm for (2) and can be assigned to one octahedraly coordinated tellurium atom in the [TeW6O24]6) kernel. This signal is slightly deshielded compared to the values for molybdotellurates [2, 10]. In compared (2), another signal is observed at 714.69 ppm, that is assigned to the Te(2)(OH)6 [21], moiety identi®ed in the X-ray structure analysis. t.g./d.s.c. studies Thermogravimetric analysis (t.g.) and differential scanning calorimetry (d.s.c.) studies were performed for both compounds. In compound (1), a ®rst step was observed (Figure 3) between 155.8 and 210 °C, with simultaneous loss of two molecules of imidazole (Found, 5.9%, Calcd. 6.3%) through an endothermic process with DH = 124.2 kJ mol)1.
691
Fig. 3. T.g. and d.s.c. curves at 5 °C min)1 in dynamic N2 atmosphere at 70 cm3 min)1 for compound (1).
Fig. 4. T.g. and d.s.c. curves at 5 °C min)1 in dynamic N2 atmosphere at 70 cm3 min)1 for compound (2).
Table 5. Crystallographic and data collection parameters Formula M Crystal system Space group Crystal size (mm) Unit cell dimensions a (AÊ) b (AÊ) c (AÊ) b (°) Volume (AÊ3) Z Density (obs) (gd cm)3) Absorption coecient (mm)1) F(000) Index range Re¯ections collected Independent Re¯ections Observed re¯ections No. of parameters re®ned Goodness-of-®t on F2 (s) Final R indicesa,b R indices (all data) Residual diraction (eAÊ)3)
(1) C24H38W6N16O24Te 2165.4 Monoclinic Cm 0.40 ´ 0.35 ´ 0.25
(2) C24H48W6N12O30Te2 2343.1 Monoclinic C2/c 0.70 ´ 0.50 ´ 0.40
9.776(2) 21.702(3) 11.1340(15) 98.89(2) 2333.8(6) 2 3.061 5.438 1936 )13 £ h £ 13, 0 £ k £ 30, )4 £ l £ 15 3490 3490 [R(INT)=0.024] 2961 [I ³ 2r(I)] 194 1.059 R1=0.060 c wR2=0.156 R1=0.075 wR2=0.166 1.254e, )0.973
17.705(7) 21.672(4) 13.996(3) 108.19(3) 5101.9(25) 4 3.043 4.695 4232 )24 £ h £ 23, )2 £ k £ 30, )3 £ l £ 19 7452 5436 [R(INT)=0.063] 3917 [I ³ 2r(I)] 328 1.151 R1=0.077 d wR2=0.229 R1=0.1113 wR2=0.272 0.965, )0.807
a
R RjjF0 j ÿ jFc j=jRjF0 j. wR2 fRw
F02 ÿ Fc2 2 =Rw
F02 2 g1=2 . c w 1=r2
F02
0:1215P 2 22:6159P . d w 1=r2
F02
0:1527P 2 23:1451P , P
F02 2Fc2 =3 for all compounds. e at
