7902
Journal of the American Chemical Society
/
100:25
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December 6 , I978
parameters for b o t h structures ( 3 1 pages). O r d e r i n g i n f o r m a t i o n is given on any current masthead page.
(1 1) Anal. Calcd for MOC12(P(C&)3): Mo, 22.36; CI, 16.52. Found: Mo, 22.60; CI, 17.30. (12) Refinement of the structure of M O ~ C I ~ ( P ( C ~isHstill ~ ) incomplete, ~)~ but all nonhydrogen atom positions have been determined and the basic structural unit Mo4C18P4is the same in all essential features as that determined for M O ~ C I ~ ( P ( C ~Crystals H ~ ) ~ ) ~of. the latter grown from benzene References and Notes were found to be monoclinic, a = 14.274 (2) A, b = 12.564 (1) A, c = 14.427 (2) A, @ = 122.80 (l)', R , l c , Z = 2. Using 2378 data of limited (1) F. A. Cotton, Chem. Soc. Rev., 4 , 27 (1975), and references cited therequality with intensities I > 3 4 0 the refinement has converged with R = in. 0.126 and R, = 0,158. In the final refinement cycles anisotropic temper(2) For some recent examples see R. J. Kiinger, W. Butter, and M. D. Curtis, ature factors were included for ail nonhydrogen atoms except for the four J. Am. Chem. SoC., 97. 3535 (1975); F. A. Cotton, M. W. Extine, and R. H. C atoms of two ethyl which had unusually large temperature fac. groups, . Niswander, Inorg. Chem., 17, 692 (1978): W. I. Bailey. Jr., M. H. Chisholm, tors. F. A. Cotton, C. A. Murillo, and L. A. Rankel, J. Am. Chem. Soc., 100, 802 (13) Other important distances and angles in the M O ~ C I ~ ( Pmolecule E ~ ~ ) ~ follow: (1978); M. H. Chisholm, R. L. Kelly, F. A. Cotton, and M. W. Extine, ibid.. MO(l)-Cl(l), 2.425 (5); M0(2)-C1(2), 2.421 (6); Mo(i)-C1(3'), 2.381 (6); 100, 2256 (1978). Mof l)-CIf4'1. 2 427 16): Mo[2)-C1[3). 2.373 15): Mo(2)-C1(4), 2.422 (5); ., ,. . ~ ~ , (3) J. San Filippo, Jr., H. J. Sniadoch, and R. L. Grayson. Inorg. Chem., 13, 2121 Mo(i)-P({), 2.558 (6(;~Mo(2)-P(2).2.556 (7) A': Mo(i)~M0(2)-'Mo(i'),90.6 (1974); J. San Filippo, Jr., Inorg. Chem., 11, 3140 (1972). ( 1)' : Mo(2)-Mo( 1)-Mo( 2'), 89.4'. (4) This composition is attained for the compound only after removal of solvent (14) The Mo-Mo single bond distance is known to vary markedly dependin on and drying in vacuo. Anal. Calcd for M O ~ C I ~ ( P ( C ~ H ~ ) ~ ) ~Mo, ( C 20.80; H~~H)~: the nature of all ligands present, from a minimum value of about 2.5 to CI, 15.37: C. 49.48; H, 4.15. Found: Mo, 20.54: CI, 15.42: C, 50.34; H, a maximum of about 3.2 A; ref 16. 4.45. (15) Representative of compounds having Mo-Mo triple bonds unsupported by (5) The crystal structure analysis revealed three sites occupied by unbound any bridging ligands are Mo2(NMe& (ref 17), Mo2(CHZSiMe3)6 (ref 18). and solvent moiecules, but less than full occupation of these sites makes n = M 0 ~ ( 0 S i M e ~ ) ~ ( N H M e ~19), ) ~ (with r e f Mo-Mo bond distances of 2.21 1 (2), 2.2. 2.167, and 2.242 (1) A, respectively. The comparison of distances in (8) The crystals were found to be-triclinic, P i , 2 = 1, a = 11.547 (6) A, b = M O ~ C I ~ ( Pand E ~M~ O ) ~~ ( O S ~ M ~ ~ ) ~is( especially N H M ~ ~ pertinent )~ because 12.152 (5)A, C = 9.458 (4) A,
