2250 Inorganic Chemistry, Vol. 18, No. 8, 1979 (43) Wagner, K. P.; Hess, R. W.: Treichel, P. M.; Calabrese, J. C. Inorg. Chem. 1975, 14, 1121. (44) Kasai, N., private communication. (45) Nakamura, A,; Yoshida, T.; Cowie, M.; Otsuka, S.; Ibers, J. A. J . A m . Chem. SOC.1977, 99, 2108. (46) Elian; M.; Hoffmann, R. Inorg. Chem. 1975, 14, 1058. (47) Rossi, A. R.; Hoffmann, R. Inorg. Chem. 1975, 14, 365. (48) Huheey, J. E. In “Inorganic Chemistry”; Harper and Row: New York, 1912; 227. (49) Amleton, T. G.:Clark, H. C.; Manzer, L. E. Coord. Chem. Reu. 1973, 10,-335. (50) Tolman, C. A. J . A m . Chem. Soc. 1970, 92, 2956. (51) Otsuka, S.; Yoshida, T.; Matsumoto, M.; Nakatsu, K. J . Am. Chem. SOC.1976. 98. 5850.
(52) Harada, M.;Kai, Y.; Yasuoka, N.; Kasai, N . Bull. Chem. SOC.Jpn., 1976, 49, 3472.
Clegg et al. (53) Pearson, R. G. “Symmetry Rules for Chemical Reactions”; WileyInterscience: New York, 1976; p 190. (54) Eaton, D. R.; J . Am. Chem. Soc. 1968, 90, 4272. (55) The preparation and structural characterization of another Pt complex containing both bridging and terminal hydrido ligands, [Pt2H2Ph(PEQ4][BPh4] (Bracher, G.;Grove, D. M.; Venanzi, L. M.; Bachechi, F.; Mura, P.; Zambonelli, L. Angew. Chem., Int. Ed. Engl. 1978, 17, 778), has recently appeared. No indication of bridge-terminal hydrido ligand exchange is observed at rmm temperature. This lack of fluxionality is presumably also a result of steric constraint. The PEt, ligands of each Pt center are mutually trans and would not be readily accommodated in the tbp geometry outlined above. The complex is best described as two distorted square-planar d8moieties sharing the bridging hydrido ligand and involving a minimal Pt-Pt interaction. Thus the complex lacks the angular strain present in complexes 1-5 which facilitates bridge bond cleavage.
Contribution from the Departments of Inorganic Chemistry, University of Manchester, Manchester M13 9PL, England, and University of Newcastle upon Tyne, Ne1 7RU, England
Preparation and Characterization of Tetraphenylarsonium trans-Bis(p-acetate)-tetrachlorodimolybdate(I1) Disolvates, [(C6H5)4As]2[Mo2(02CCH3)2C14]-2L (L = H 2 0 or CH30H) WILLIAM CLEGG,*Ia C. DAVID GARNER,*Ib STEPHEN PARKES,Ib and IAN B. WALTONIb Received December 15, 1978
The preparation and isolation of [(C6HS)4As]2[Mo2(02CCH3)2C14].2L (L = H 2 0 or C H 3 0 H ) are reported. The methanolate crystallizes in the triclinic space group Pi with a = 10.571 (2) A, b = 11.330 (2), A, c = 13.397 (2) A, a = 75.16 (l)’, P = 67.19 (l)’, and y = 64.24 (1)’. The structure has been determined from 2165 X-ray counter intensities by Patterson and Fourier techniques and refined by full-matrix least-squares methods to R = 0.058 (0.073 weighted). The unit cell contains one centrosymmetric [ M o ~ ( O ~ C C H ~ ) ~two C ~ [(C,H,)4As]f ~]~-, ions, and two C H 3 0 H moieties. The anion has the trans configuration and closely approximates to D2hpoint symmetry with dimensions Mo-Mo = 2.086 (2), Mo-0 = 2.120 (13), and Mo-C1 = 2.434 (4) %.;the methanol molecules are not coordinated to the molybdenum atoms. Vibrational and electronic spectral data are reported for this material. The v(Mo-Mo) stretching frequency of 380 cm-’ and the position of the first absorption maximum at 20 200 cm-’ are midway between the corresponding values of Mo2(02CCH3), and [ M O ~ C ~ ~even ] ~ -though , the Mo-Mo bond length for [ M O ~ ( O ~ C C H ~ ) ~is Cthe I ~ shortest ]~of these three complexes. least-squares refinement based on the observed and calculated positions of spots on (Okl), (hOl), and (hkO) photographs. There were no systematic absences. The crystal chosen for refinement of cell parameters and collection of intensities had a maximum dimension of ca. 0.35 mm. It was mounted on a Hilger and Watts Y290 four-circle diffractometer, with c* a few degrees misaligned from the instrument @J axis. Unit cell parameters and the orientation matrix were refined by a least-squares technique’ based on the automatically determined setting angles at room temperature of 12 reflections with 34’ < 28 < 41’ (MoKa properties of the bis(p-acetat0)-tetrachlorodimolybdenum(I1) radiation; Z r filter). Values obtained were a = 10.571 (2) A, b = complex, t r a n s - [ M 0 ~ ( 0 ~ C C H ~ ) ~Spectral C l ~ ] ~properties -. of 11.330 (2) A, c = 13.469 (2) A, a = 85.05 (l)’, P = 66.47 (l)’, and this anion are discussed with reference to the corresponding y = 64.24 (1)’. This corresponds to a type I reduced cell* with a properties of M o 2 ( O Z C C H 3 ) , a n d [Mo2C1,I4-. = 10.571 (2) A, b = 11.330 (2) A, c = 13.397 (2) A, a = 75.16 (I)’, Experimental Section fl = 67.19 (l)’, and y = 64.24 (1)’; the matrix for transformation or from initial cell to reduced cell is (-1, 0, 0; 0, -1, 0;-1, 0,1). Data Preparation of [ (C6H5)4A~]2[Mo2(02CCH3)2C14].2L (L = were collected, reduced, and corrected for absorption on the basis of CH30H). Mo2(O2CCH3)? (1.0 g, 2.34 mmol) was added to a solution of Ph4AsC1 (Aldrich, 1.92 g, 4.68 mmol) in deionized, degassed water the initial cell and then transformed to correspond to the reduced cell (65 cm3) under an atmosphere of purified nitrogen. Concentrated for all other calculations. hydrochloric acid (20 cm3), previously purged with nitrogen, was added The unit cell volume (1324.6 A3) and formula weight (1282.6) give dropwise with stirring to this solution. After ca. 8 h the orange Z = 1 for a density of 1.608 g ~ m - The ~ . density was measured as precipitate which had formed was removed by filtration, washed twice 1.60 f 0.01 g cm-’. For sptce group P1, no symmetry is imposed with degassed, deionized water (10 cm3) and methanol (2 X 5 cm3), on the structure, but for P1, the dimeric anion must be centroand dried in vacuo. Yield of [(C6H5)4As]2[Mo2(02CCH3)2C14].2H20 symmetric. Pi was assumed and was confirmed by successful structure was typically ca. 2 g (ca. 75%). Anal. Calcd for C52H500&2C14M02: solution and refinement. C, 49.8; H , 4.0; As, 11.9; C1, 11.3; Mo, 15.3. Found: C, 49.7; H, Intensities were collected at room temperature for all independent reflections with 28 5 45’. A 8-28 scan was used, with a 1-s count 3.9; As, 11.2; CI, 11.7; Mo, 15.4. Crystals of [(C,H,),at each of 80 steps of 0.01’ for each reflection and a 20-s background AS]~[MO~(O~CCH~)~C~~].~CH~OH suitable for X-ray crystallographic count at each end of the scan range. No reflections were sufficiently studies were obtained by recrystallization from degassed AnalaR methanol. intense to require the insertion of attenuators into the beam. The Data Collection and Reduction. The dark red crystals were irregular data were corrected for Lp factors, absorption, and crystal decay.g in shape. Initial values of the triclinic cell parameters were obtained Absorption corrections were of the Gaussian integration type (,u 20.20 from precession photographs (Mo Ka radiation, 0.71069 A) by a cm-’, 96 grid points), with the crystal approximated by six planar Introduction A large n u m b e r of compounds containing metal-metal quadruple bonds have now been c h a r a ~ t e r i z e d ,including ~,~ a considerable range of compounds containing the Mo;’ center. Two p a r e n t complexes, f r o m which a l a r g e n u m b e r of these derivatives have been prepared, are M o 2 ( O 2 C C H 3 ) ? a n d [ M O ~ C ~ ~Herein6 ] ~ - . ~w e report the isolation, X - r a y crystallographic characterization, and c e r t a i n spectroscopic
0020-1669/79/1318-2250$01.00/00 1979 American Chemical Society
Inorganic Chemistry, Vol. 18, No. 8, 1979 2251 Table I. Atomic Coordinates (X Parameters (AZx 1o3)aSb atom
X
Mo Cl(1) Cl(2) O(1) O(2) C(1) C(2) AS C(11) C(12) C(13) C(14) C(15) C(16) C(21) C(22) C(23) C(24) C(25) C(26) C(31) C(32) C(33) C(34) C(35) C(36) C(41) C(42) C(43) C(44) C(45) C(46) O(S0l) $(Sol)
-179 (1) 2112 (4) -2742 (4) 419 (9) -768 (9) 749 (14) 1120 (19) -1677 (1) -2540 (12) -3412 (14) -4145 (15) -4008 (15) -3111 (15) -2444 (14) -2792 (13) -4043 (14) -4774 (15) -4289 (14) -3109 (15) -2318 (15) 340 (12) 860 (15) 2316 (16) 3228 (17) 2740 (18) 1269 (17) -1737 (13) -2599 (15) -2629 (18) -1792 (18) -905 (19) -897 (16) 4381 (19) 4713 (35)
Y
and Isotropic Thermal
Table 11. Anisotropic Thermal Parameters (AZ X lo3)' atom
Z
U
360 (1) -752 (1) -572 (3) -2203 (3) 1869 (3) -448 (3) 1987 (7) -920 (6) -714 (6) -1210 (7) 2060 (12) -139 (11) 3235 (15) -201 (12) 4518 (1) 3749 (1) 6043 (11) 4494 (9) 45 (3) 5973 (13) 5589 (10) 60 (4) 7102 (14) 6116 (11) 69 (4) 8292 (14) 5592 (11) 69 (4) 8323 (14) 4533 (11) 70 (4) 7235 (13) 3965 (11) 62 (4) 4812 (11) 2819 (9) 46 (3) 5939 (12) 2818 (10) 57 (3) 2106 (11) 64 (4) 6124 (13) 5179 (12) 1421 (10) 59 (3) 4063 (13) 1462 (11) 65 (4) 3822 (13) 2147 (10) 61 (4) 2885 (9) 42 (3) 4141 (11) 2266 (11) 65 (4) 5100 (13) 4725 (14) 1574 (11) 72 (4) 3473 (15) 1488 (12) 76 (4) 2497 (17) 2098 (13) 90 (5) 2851 (15) 2801 (12) 82 (5) 3025 (11) 4822 (9) 47 (3) 2358 (13) 4885 (11) 68 (4) 1313 (16) 5736 (13) 86 (5) 998 (17) 6370 (14) 89 (5) 1592 (17) 6308 (14) 99 (5) 2669 (15) 5480 (12) 79 (4) 568 (17) -2058 (15) 179 (7) 503 (32) -969 (28) 221 (14)
'
In this and subsequent tables, estimated standard deviations in the last place of figures are given in parentheses. The isotropic 1. temperature factor takes the form exp[-8n2(sin2 e)u/h2 faces (010, 010, 210, 210, 001, and 001 at distances 0.222, 0.022, 0.022,0.158,0.135, and 0.135 mm, respectively, from a common point inside the crystal, measured with a high-power microscope and calibrated graticule). Transmission factors range from 0.526 to 0.664. Decay corrections were based on the periodic measurement of three standard reflections, the intensities of which fell by a total of 15.4, 14.7, and 11.1% during the data collection. Intensities and their estimated standard deviations were calculated as reported previously,10 with p = 0.05. Of the 3785 measured independent reflections, 431 had I < 0, and 2165 with I > 3u(I) were used for structure solution and refinement. Structure Solution and Refinement. All nonhydrogen atoms, other than those of methanol, were determined from Patterson and subsequent Fourier syntheses. Refinement was by full-matrix least-squares methods; the quantity minimized was CwA2 with w = (u2(Fo)+ OsO02F2}-l and A = lFol - IFJ. Refinement began with isotropic thermal parameters and rigid idealized phenyl rings; constraints were gradually removed as refinement continued. Whenever the model was altered and more parameters were introduced, the decrease in R (=CIAl/CIFol)and R, (=(CwA2/CwF2)'/*) was tested" and found to be highly significant (significant at the 0.5% level in all cases). Atomic scattering factors for uncharged atoms, including corrections for anomalous scattering, were taken from ref 12. With Mo, C1, As, and acetate atoms anisotropic and phenyl carbon atoms isotropic, R was 0.080 and R, 0.1 19. A difference map revealed two peaks assigned to methanol, not coordinated to the Mo atoms. The larger of these was refined as oxygen, the smaller as carbon, with isotropic thermal parameters. With R at 0.059 and R, 0.075, another difference map contained peaks at most of the positions expected for hydrogen atoms. H atoms were included in the refinement, but their positions were calculated for idealized geometry (external bisectors of C-C-C angles for phenyl H, tetrahedral angles for CH3, and C-H = 0.95 A 13) and constrained to these geometries during refinement. No hydrogen atoms were included for the methanol. Two isotropic thermal parameters were refined: one for the phenyl and one for the
uz2
ull 52.5 (8) 8 4 (3) 68 (2) 74 (6) 66 (6) 52 (8) 131 (15) 50.6 (9)
37.3 (6) 65 (2) 59 (2) 38 (5) 45 (5) 43 (8) 73 (10) 46.2 (8)
u3, 35.4 (6) 47 (2) 77 (2) 45 (5) 52 (5) 56 (8) 85 (11) 38.8 (7)
'23
4.0 (5) -7 (2) -3 (2) 2 (4) -2 (4) -2 (6) -6 (9) 3.5 (6)
Ul3
u,,
-13.1 (6) 5 (2) -37 (2) -20 (5) -16 (4) -3 (7) -12 (10) -12.3 (6)
-22.3 (6) -37 (2) -19 (2) -24 (4) -29 (4) -22 (6) -70 (11) -24.6 (7)
a The anisotropic temperature factor takes the form exp[-2nz. (haa*2U,l+ . . + 2hka*b*U12 + . ..)I.
.
Table 111. Calculated H Atom Coordinates (X 10")' atom H(1) W2) H(3) ~(13) W14) W15) HU6) H(22) ~(23) ~(24) H(25) H(26) H(32) M33) H(34) W35) H(36) ~(42) W43) W44) W45) W46)
X
Y
Z
1356 290 1944 -3494 -4756 -4530 -2940 -1919 -4392 -5621 -4789 -2808 - 1495 236 2672 4214 3382 916 -3134 -3238 -1836 -330 -286
3178 4024 3240 5162 7063 9065 9107 7304 6576 6904 5322 3418 3021 6004 5 393 3257 1597 2178 2585 84 1 285 1315 3132
430 -243 -831 5963 6854 5958 4182 3208 3303 2084 920 996 2172 2309 1144 1005 205 1 3222 4391 5851 6923 6782 5380
.
Group isotropic thermal parameters are U = 0.119 (34) methyl and U = 0.144 (15) Az for phenyl H atoms.
for
methyl hydrogen atoms. The final values of R and R, were 0.058 and 0.073. The largest shift/esd ratio for the atomic coordinates in the last cycle was 0.020, and for the thermal parameters it was 0.007. The value of S ( = ( C w A 2 / [ N for N reflections and P (=180) refined parameters was 1.10; the root-mean-square deviation of a reflection of unit weight on an absolute scale of Fc (=(CwA2/Cw)"2) was 2.52 electrons and showed no systematic trends with indices, sin 8, or F,. The weighting scheme was thus shown to be c o n ~ i s t e n t . ' ~ No extinction correction was indicated as necessary by a comparison of Faand F, for strong, low-angle reflections. A difference synthesis after the final cycle showed no peaks higher than 1.07 e A-3,the largest being close to the heaviest atoms, and no depressions lower than -0.88 e .k3. The two methanol atoms had high thermal parameters and a separation of 1.605 (33) A, indicating a degree of disorder in the solvent of crystallization. There were no significant differences between lFcl and IFo]for the reflections with 0 C I < 3a(I) omitted from the refinement. Inclusion of them gave R = 0.096 and R, = 0.086; one refinement cycle produced no shift/esd ratio greater than 0.8 and no significant change in R and R,. Observed and calculated structure factors on an absolute scale (electrons) are tabulated as supplementary material. Positional and thermal parameters are given in Tables 1-111, interatomic distances and bond angles in Table IV, and selected least-squares planes fitted to atomic positions in Table V. The atomic arrangements within the cations and anions are presented in Figures 1 and 2, respectively, and the crystal packing is shown in Figure 3. There are no unusually short interatomic contacts. Spectroscopic Measurements. IR spectra were recorded on a Perkin-Elmer 257 spectrophotometer and Raman spectra on a Cary 82 instrument by using 6328-A excitation. Room-temperature electronic absorption spectra (8500-2000 A) for these compounds dissolved in H 2 0 and C H 3 0 H were recorded with a Perkin-Elmer
2252 Inorganic Chemistry, Vol. 18, No. 8, 1979
Table V. Least-Squares Planes in 'Term3 of Orthogonal Angstrom Axes along a h , c X a * , and c
Table IV
As-C( 11) As-C( 21 ) C(1l)-C(12) C(12)-C(13) C(13)-C(14) C(14)-C(15) C(15)-C(16) C(16)-C(ll) C(31)-C(32) C(32)-C(33) C(33)-C(34) C(34)-C(35) C(35)-C(36) C(36)-C(31) Mo-Mo' Mo-Cl(1) Mo-Cl(2) Mo-O(l)
Cation Bond Lengths (A) 1.903 (11) As-C(31) 1.906 (12) As-C(41) C(21)-C(22) 1.401 (16) C(22)-C(23) 1.383 (17) C(23)-C(24) 1.392 (18) 1.369 (17) C(24)-C(25) C(25)-C(26) 1.381 (18) C(26)-C(21) 1.382 (16) C(41)-C(42) 1.369 (16) C(42)-C(43) 1.391 (17) 1.329 (18) C(43)-C(44) 1.365 (19) C(44)-C(45) C(45)-C(46) 1.407 (20) 1.366 (17) C(46)-C(41) Anion Bond 2.086 (2) 2.437 (3) 2.430 (4) 2.131 (8)
Lengths (A) M0-0(2) C(l)-O(l) C(1)-O(2)' C(l)-C(2)
1.902 (11) 1.926 (11) 1.383 (16) 1.371 (17) 1.382 (17) 1.343 (17) 1.373 (18) 1.415 (16) 1.383 (17) 1.420 (19) 1.336 (20) 1.342 (21) 1.424 (20) 1.357 (17) 2.108 (8) 1.255 (15) 1.293 (15) 1.518 (17)
Solvent Bond Length (A) C(sol)-O(sol) 1.605 (33) Cation Bond Angles (deg) C(ll)-A~-C(21) 107.5 (5) C(21)-As-C(31) C(lI)-As-C(31) 113.7 (5) C(21)-As-C(41) C(11)-A~-C(41) 108.1 (5) C(31)-As-C(41) 118.2 (9) As-C(21)-C(22) As-C(11)-C(12) A~-C(ll)-C(16) 122.0 (9) A~-C(21)-C(26) C(16)-C(ll)-C(l2) 119.5 (11) C(26)-C(21)
