Tetraphenylphosphonium TricNorocuprate(I1)
Inorganic Chemistry, Vol. 13, No. 6,I 9 74 136 1 Contribution from the Institut fur anorganische Chemie, Universitat Zurich, Ramistrasse 76,8001 Zurich, Switzerland
Crystal and Molecular Structure of Tetraphenylphosphonium Trichlorocuprate(II), (c~H,)~Pcuc&,a Complex Containing Nonplanar Dimeric [cu2c16l2- Units M. TEXTOR, E. DUBLER, and H. R. OSWALD*
AIC30660B
Received September 10, 1973 The crystal structure of tetraphenylphosphonium trichlorocuprate(II), (C,H,),PCuCl,, has been determined by conventional Patterson, Fourier, and least-squares refinement techniques with data collected on an automated fourcircle diffractometer. The complex crystallizes in the centrosymmetric space group P2,/c with a = 9.226 (8) A, b = 19.301 (15) A, c = 13.842 (15) A , p = 111.26 (6)", and Z = 4 . The structure was refined to a conventional discrepancy factor of 0.032 for 1189 observed reflections. The function minimized during the refinement process was C w ( IFoI - IFcI)'. All atoms including the hydrogens of the phenyl rings have been located. The structure contains completely isolated [Cu,C1,]'- dimers with two bridging and four terminal chlorines and a C u C u distance of 3.355 (1) A. The dimeric units are distinctly nonplanar, the angle between the plane defined by the copper and the two terminal chlorines and the plane defined by the copper and the two bridging chlorines being 50". The coordination about each copper is between a planar and a tetrahe? dral arrangement of four chloride ligands. The C u C 1 bond distances to the terminal chlorines (2.200 (2) and 2.179 (3) A) are considerably shorter compared to the bridging ones (2.292 (2) and 2.321 (2) A). Both terminal and bridging chlorines are significantly displaced from a symmetrical position relative to the copper central atoms. The shortest distance of about 9 A between different [Cu,C1,Iz- dimers rules out any further coordination about the copper atom by additional chlorine atoms. The (C,H,),P' cations are separated from the dimeric units by normal van der Waals contacts (shortest C1-C distance 3.54 A). Tetraphenylarsonium trichlorocuprate(II), (C,H,),AsCuCl,, is isomorphous with a = 9.298 (8) A, b = 19.596 (11) A, c = 13.743 (9) A, and (3 = 111.60 (5)". Electronic reflection spectra and the expected magnetic behavior of the complexes under study are briefly discussed.
Introduction kK? typical for an octahedrally distorted environment of copper(I1). Ludwig and Textor' reported on spectroscopic studies of While one could not expect the presence of three-coordinate chloro and bromo complexes of copper(I1) formed in noncocopper(I1) in the solid complexes under investigation, the ordinating organic solvents such as methylene chloride at energy of their ligand field transitions pointed to a new local various concentrations of copper(I1) and halide ions. In the symmetry about the copper somewhere between a planar special case where the ratio [Cu"] : [X-] = 1:3 (X = C1, Br) and a tetrahedral coordination. only one complex species exists in observable concentration. Molecular weight determination, as well as electronic and Experimental Section infrared spectra, favored the assumption of a monomeric Preparation of (C,H,),PCuCl,. Saturated solutions of (C6H5),three-coordinate complex [CuX3]-. From these solutions it PCl and CuCI, in absolute ethanol were poured together in equimolar is possible to isolate complex salts of the type (cation)CuX3, proportions. Red-brown platelike crystals separated immediately and were collected. They were recrystallized from hot absolute where cation stands for the bulky tetraphenylphosphonium, ethanol and dried in a vacuum desiccator. Anal. Calcd for (C6Hs),tetraphenylarsonium, or tetrabutylammonium group. PCuC1,: C, 56.60; H, 3.96;Cu, 12.48. Found: C, 56.75; H , 4 . 0 3 ; Structural investigations on complexes of the same stoichiCu, 12.38. ometry, but with smaller cations like the garnet-red KCuCl3? Growth of Single Crystals. An ethanolic solution of (C6H5),PCuCl, saturated at 50" is slowly cooled to room temperature over a N H ~ C U Cand ~ ~ (CH3)2NH2CuC13,3 ,~ have been shown to 48-hr period. The resulting prismatic crystals are stable to air and do contain discrete planar [cu2c16]2- ions. The dimers in not decompose upon exposure to X-rays. KCuCl, and NH4CuC13 are stacked above each other in such Unit Cell and Space Group. Weissenberg photographs taken on a a way that each copper is bonded to a chlorine atom in the Nonius camera with Cu KCYradiation and precession photographs dimer above it and to a chlorine atom in the dimer below it. taken on a Buerger precession camera with Mo Ka radiation indicated that the crystals belong to the monoclinic system, The systematic In this manner the copper atom completes its distorted octaabsences h01 for 1 = 2n -t 1 and OkO for k = 2n t 1 are consistent hedral coordination. The situation in (CH3)2NH2CuC13is with the centrosymmetric space group P2,/c ( c , h 5 ) . Accurate unit comparable, except for the sixth position of the distorted cell dimensions were calculated from X-ray powder photographs octahedral configuration remaining unoccupied, which results registered on a Guinier-de Wolff focusing camera using Cu Kor radiain formally five-coordinate copper(I1). tion and high-purity potassium chloride as an internal standard, The lattice constants refined by least-squares methods from 30 powder Spectral investigations in the visible and ultraviolet regions are a = 9.226 (8) A, b = 19.301 (15) A, c = 13.842 (15) A , Of (C&5)4PCUC13, (C6&)4ASCUC13, and ( C ~ H ~ ) ~ N C U C reflections ~~~ and p = 111.26 (6)". The unit cell volume is 2297 A3. The pycnoshowed that there is no striking similarity to those complexes metrically measured density (pobsd = 1.46 f 0.01 g cm-') is in good containing the planar [cu2c16]2- mentioned above. This agreement with the calculated value Pcdcd = 1.47 g cmW3and 2 = 4. holds especially for the ligand field part of the spectra, which Collection and Reduction of the X-Ray Diffraction Data. A (C,H,).,PCuCl, single crystal with approximate dimensions 0.17 X contains in the case of the former complexes with bulky 0.13 X 0.08 mm was chosen for data collection on an automated fourcations a band at some 8 kK and a shoulder at 11.1 kK while circle Picker diffractometer using Mo KCY radiation (pyrolytic the known planar dimers exhibit one broad absorption at graphite monochromator, 002). Intensity data were collected by a about 12.9 kK with a weak shoulder in the range of 10.5-11.5 conventional moving-crystal, moving-counter 8-28 scan over a 20 (1) 471. Ludwig and M. Textor, Hetv. Chim. Acta, 54, 1143 (1971). (2) R. D. Willett, C. Dwiggins, R. F. Kruh, and R. E. Rundle, J. Chem. Phys., 38, 2429 (1963). (3) R. D. Willett, J. Chem. Phys., 44,39 (1966).
range of 1.5" with a scan speed of 0.25"/min. Background counts of 100 sec were taken at each side of the peak. Three selected standard reflections were measured after every 10 reflections and used for an internal scaling of the data by least-squares methods. The average standard deviations of the intensities from the (4)R. D. Willett and 0. L. Liles, Znorg. Chem., 6, 1666 (1967).
1362 Inorganic Chemistry, Vol. 13,No. 6,1974 fit with the regression lines are 1.0,0.6, and 1.2% for the three standard reflections. Intensities were collected up to 20 < 35". Of the 2098 reflections measured (including standards), 1460 remained after averaging equivalent reflections and 1189 were judged to be observed according to the criterion Z > 2a(I), u(Z) being the estimated standard deviation in the net intensity based on counting statistics. The intensities were reduced to Fo in the usual way by applying Lorentz and polarization factors. Absorption corrections ( p = 14.0 cm-' for Mo Kor) were made by an enlarged versions of the program ORABS 2 6 and resulted in a significantly better agreement between intensities of measured equivalent reflections. The calculated transmissions varied from 0.842 to 0.898. Solution and Refinement of the Structure. A three-dimensional Patterson synthesis revealed the positional parameters of the copper, two chlorine, and the phosphorus atoms. The unweighted discrepancy factorR(ZIIF,I- l F c l l / X I F o l ) at this point wasabout 0.39. By two successive threedimensional difference Fourier syntheses the positions of the still missing chlorine atom and of all carbon atoms were detected. Full-matrix isotropic least-squares refinement on the positional and thermal parameters of all nonhydrogen atoms resulted in an unweighted R value of 0.087 and a weighted discrepancy factor of R w = 0.091, where R, = [Xw(IFoI - IFc1)2/CwlFo I']'''. The function minimized was cw(iFol- lFcI)',where w is the weight derived from counting statistics and defined as w = l/02(F,). Refinement was continued using anisotropic thermal parameters. Three cycles of refinement of thermal and two cycles of positional parameters converged to R = 0.053 andR, = 0.058. A subsequent three-dimensional difference Fourier map showed 20 peaks with peak heights between 0.7 and 1.0 e/A3,which could be attributed to the hydrogens of the phenyl rings. The variation of the positional parameters of the hydrogens resulted in a substantial improvement of the C-H distances and C-C-H angles. Inclusion of the hydrogen atoms decreased R to 0.042 and R, to 0.041. The isotropic thermal parameter B for all the hydrogen atoms was chosen as 6.0 A' and held invariant during the refinement process. A further refinement cycle of the thermal and positional parameters of all nonhydrogen atoms yielded the final values' R = 0.032 and R, = 0.024. The largest ratio of the shifts of the atomic positional parameters to the standard deviations in the last full-matrix refinement cycle was
