Department of Chemistry, The University of Akron. Akron, Ohio 44325. (Received October 8, 1985). Abstract. The structure of bis(acetylacetonato)copper(II) has ...
Journal of Crystailographic and Spectroscopic Research, VoL 16, No. 6, 1986
Crystal structure of bis(2,4-pentanedionato)copper(II) P. C. LEBRUN, W. D. LYON, and H. A. KUSKA* Department of Chemistry, The University of Akron Akron, Ohio 44325 (Received October 8, 1985)
Abstract
The structure of bis(acetylacetonato)copper(II) has been redetermined from single crystal X-ray diffraction data. The unit cell parameters are a = 11.331 (9), b = 4.697(3), c = 10.290(9) .~, and/3 = 91.84(7) ~ A final R = 0.056 for 727 observed reflections was obtained. The O-Cu-O chelate (bite) angle is 93.2(2) ~ The two Cu-O bond lengths are 1.914(4) and 1.912(4) A. The complex has a slight chair structure and a step angle of 7.05 ~
Introduction
This laboratory has been involved in preparing and characterizing mixed ligand complexes of Cu(II). Recently these studies have been extended to determining the effects of mixed ligand formation on the bond distances and angles. To get maximum information from these studies, it is desirable to have the corresponding information for the nonmixed complexes. Although bis(2,4pentanedionato)Cu(II) has been previously studied by three-dimensional X-ray diffraction (Starikova et al., 1969), this early study is not precise enough (R -0.151) for this purpose.
Experimental
Weissenberg and oscillation methods confirmed the monoclinic symmetry and P21/n space group. A syntex P2~ four-circle computer-controlled diffractometer was used to obtain cell constants and an orientation matrix from a leastsquares fit (s = 0.71) of 12 reflections (10 < 2 0 < 21.5~ The intensities of 872 ( + h , +k, +/; quadrant) independent reflections 889 0277-8068/86/1200~0889505,00/0 9 1986 Plenum PuNishing Corporation
LeBrun eta|.
890
Table 1. Summary of data collection and processing parameters for Cu(acac)2 Molecular formula Molecular weight Crystal dimensions (ram3) Space group a (~) b (A) c (A) 13(deg) Vc(,~ 3) Molecules per cell De, g cm-3 Do, g cm-3 F(000) /x (Mo Ko0 (cm-l) (Mo Ka), graphite monochromator Collection range Independent data Total parameters R
CuO4CIoHI4 261.76 0,2 • 0.5 x 0.06 P2 ~/ n
11.331(9) 4..697(3) 10.290(9) 91.84(7) 547.4(7) 4 1.59 1.586 270 20,6 0.71069 < 2 0 _< 45 ~ 757 175 0.056
were measured at room temperature out to 20 of 45 ~ Three check reflections measured at 50-reflection intervals showed no significant systematic variation during the 12.76-hour X-ray exposure time. Exclusion of 115 systematically absent reflections led to a set of 757 independent observations. The data were corrected for Lorentz and polarization effects. The calculations were done using the CRYM program system (Westphal, 1975). The atomic scattering factors were those contained in CRYM except for the values for copper(II) which were taken from the International Tables (Lonsdale, 1968) corrected for anomalous dispersion (Cromer, 1974). The structure was solved by the direct methods, multi-solution weighted tangent formula MULTAN (Main et al., 1974). Absorption correction factors were applied to the data by the use of the program ORABS in CRYM. The transmission coefficients ranged from 0.67 to 0.88. The least-squares function minimized was ~w2(k 2 I f o l 2 - f c j2)2, w = 1 / ( o (F 2o)). All reflections were included in refinement except those for which the observed intensity was below background. The crystal and X-ray diffraction data and processing parameters are given in Table 1. The positions of the eight nonhydrogen atoms of one asymmetric unit were refined by full-matrix least squares with anisotropic thermal parameters. The positions of all hydrogen atoms were generated geometrically, located on a difference map, and included in the refinement with a fixed isotropic thermal parameter value of 2.1 •2. In the final cycle of refinement, the largest shift per estimated standard deviation was 0.1 (0.2 for one hydrogen coordinate). The
Structure of CuO4CloH14
891
Table 2. Cu(acac)2fractional atomic coordinates (x 104 for nonhydrogen atoms; X 10 3 for H)
Cu 0(l) 0(2) C(1) C(2) C(3) C(4) C(5) H(1) H(2) H(3) H(4) H(5) H(6) H(7)
x
y
z
0 1338(3) 62(3) 1859(5) 1582(5) 730(5) 2824(7) 517(8) 201(4) 252(6) 354(5) 305(5) 40(5) 49(6) 119(5)
0 1971(9) 2012(9) 4064(14) 5208(14) 4141(13) 5272(19) 5477(16) 691(12) 614(15) 454(11) 669(13) 385(12) 693(13) 562(12)
0 -648(4) 1616(4) -111(6) 1066(6) 1895(6) -875(9) 3161(8) 129(5) -120(7) -51(5) -49(6) 377(5) 312(7) 370(6)
final difference Fourier map showed maximum positive density of 0.46 e A -3 and minimum of - 0 . 7 6 e A - 3 associated with the Cu atoms. The final positional parameters are given in Table 2.
Results and Discussion Atomic numbering, bond lengths, and angles are shown in Fig. 1. The copper atom is located on a crystallographic center of symmetry. The molecules are stacked along the b axis. The normal to the chelate plane makes an angle of 49.9(2.2) ~ with the b crystal axis. The O - C u - O chelate (bite) angle is 93.2(2) ~ The two C u - O bond lengths of 1.914(4) and 1.912(4) A are statistically equivalent. These compare with recently summarized (Aruffo et al., 1983) averages of 92.9(1) ~ and 1.914(2) A for other bis Cu(acac)2 type complexes. The chemically unique acac ligand mean bond distances C - O = 1.27(1) A , C - C H = 1.39(1) A , and C - C H 3 ~--- 1.48(1) A do not differ significantly from those reported (Lingafelter et al., 1966) for 13 three-dimensionally determined acac complexes. The mean angles are C u - O - C = 125.9(6) ~ O - C - C H ----- 124.4(8) ~ and O - C - C H 3 -~- 114.4(8) ~ and the ring C - C - C angle is 125.4(6) ~. The shortest intermolecular distance, 2.64(8) ~ ,~, is between methyl hydrogens. The shortest copper intermolecular contact, 2.98(5) A , is to a neighboring ring hydrogen. The copper-carbon distance is 3.059(6) A . This intermolecular contact is essentially perpendicular to the primary CuO4 bonds and to the chelate rings making the stereochemistry around the Cu(II) ion planar or extremely elongated octahedral, depending on whether or not the carbon atoms are considered to be involved in semicoordinate bonding to the Cu(II) ion.
892
LeBrun et al.
114,1" (0,6) 120,9" (0.61
126.0'
25.0"
(0,4)
(0,5)
95,2" (0.2)
125.~"
(0.61
125,8"
121.5"~ (0.6),
'5)
125.8" (0~)
114.7"
(0.5)
Fig. 1. Cu(acac)2 bond lengths (A) and angles (deg) with their estimated standard deviations in parentheses.
Table 3. Cu(acac)2 planes Equations of planes in orthogonal coordinate system: I
0.6603x' - 0.6097y' + 0.4385z' - 0.1652 = 0
II
-0.6371x' + 0.6439y' - 0.4236z' + 0.0575 = 0
III
-0.5933x' + 0.7024y' - 0.3933z' = 0
wherex' = ax + cz cos ~, y' = by, and z' = cz sin ~. Displacements from plane (A); asterisks indicate atoms used to define plane: Plane I Cu
Plane II
Plane III
0.057*
0.000" 0000" 0.000"
Ol 02
-0.006* -0.001"
-0,044" -0.049*
C(1) C(2) C(3) C(4) C(5)
0.015" -0.015" 0.009*
-0.010" 0.048* -0.003* -0.023 0.030
Structure of CuO4CloHl4
893
Table 3 lists deviations of atoms from least-squares planes. The CuO4 coordination plane is crystallographically required to be planar. The dihedral angle, defined as the angle between the normal to the chelate group, plane I, and that to the plane of the copper and oxygen atoms, plane III, is 7.05 ~ . Thus, the essentially coplanar acac ligands exhibit the folding along the oxygen-oxygen lines commonly found in 4-coordinate copper complexes with/3-diketones and other planar ligands (Maslen et al., 1975). This gives rise to a slightly stepped structure for the Cu(acac) 2 molecule. A small stepped conformation is not expected to have a major effect on inter-ring 7r conjugation (Maslen et al., 1975).
References Aruffo, A., Anderson, L. D., Lingafelter, E. C., and Schomaker, V. (1983) Acta Crystallogr. C 39, 201. Cromer, D. T. (1974)International Tables for X-ray Crystallography, Vol. IV (The Kynoch Press, Birmingham, England, p. 149). Lingafelter, E. C., and Braun, R. L. (1966) J. Am. Chem. Soc. 88, 2951. Lonsdale, K. (1968) International Tables for X-ray Crystallography, Vol. III (The Kynoch Press, Birmingham, England, p. 204). Main, P., Woolfson, M. M., Lessinger, L., Germain, G., and Declercq, J.-P. (1974) MULTAN74. Programs for the automatic solution of crystal structures Universities of York, England and Louvain-la-Neuve, Belgium). Maslen, H. S., and Waters, T. N. (1975) Coord. Chem. Rev. 17, 137. Starikova, Z. A., and Shugam, E. A. (1969) Zh. Strukt. Khim. 10, 290 (Engl. Transl., 10, 267). Westphal, B, J. (1975) The CRYM Manual, Version 2 (California Institute of Technology, Pasedena, California. British Library Lending Division Supplementary Publication No. 67000 contains 6 pages of tables of temperature factors and structure factors.
