ORGANOMETALLIC CHALCOGEN COMPLEXES .15. MOLECULAR STRUCTURE OF A MOLYBDENUM (PI-CH2SCH3) COMPLEX - MO(PI-C5H5)(CO)2(PI-CH2SCH3)

A structural determination of the King-Bisnette complex Mo(π-C5H5)(CO)2(π-CH2SCH3) has shown that the CH2SCH3 ligand does not at all behave as a olefinic-like unidentate ligand but instead effectively simulates an allylic group in its functioning as a bidentate ligand. The formulation of this ligand in the metal complex as a 7r-bonding, three-electron neutral donor (with two spin-paired electrons in the π orbital and one unpaired electron in the π* orbital) is conceptually preferred even though the observed H2C-S bond length value of 1.78 ± 0.01 Å is not indicative of any significant degree of multiple bond character. A comparison of its structural features with those of Mo(π-C5H5)(CO)2p-CH3C6H4CH2) and other related Mo(π-C5H5)(CO)2XY complexes is given. The relatively similar orientations of the (CH2SCH3) ligand and the allylic part of the (P-CH3C6-H4CH2) ligand with respect to the common Mo(π-C5H5)(CO)2 fragment are found to be in accord with the stereochemical equivalence of the sulfur atom with two of the allylic carbon atoms. Crystals of Mo(π-C5H5)(CO)2(π-CH2SCH3) are monoclinic with four monomeric molecules in a unit cell of symmetry P21/n and dimensions α = 13.57 ° 0.02 Å, b = 7.97 ± 0.01 Å, c = 9.70 ± 0.01 Å, γ = 97° ± 20ʹ. A full-matrix anisotropic-isotropic least-squares refinement with three-dimensional photographic data resulted in discrepancy factors of R1 = 8.3% and R2 = 9.9%. © 1969, American Chemical Society. All rights reserved.