The complex Mo2OS(μ-S2)(S2CNR2)2 (R2 = Me2, Et2, n-Bu2, (CH2)5) was synthesized by the reaction of K2MoS4 and NaS2CNR2 in water in the presence of Na2S2O4 and by the reaction of cis-MoO2(S2CNR2)2 or Mo2O2(μ-O)(S2CNR2)4 with hydrogen sulfide in chloroform. It could not be prepared by oxo-sulfido exchange with mixtures of Mo2O2(μ-S2)(S2CNEt2)2 and Mo2S2(μ-S2)(S2CNEt2)2 nor by the reaction of elemental sulfur with Mo2O2(μ-S2)(S2CNEt2)2. The structure of Mo2OS(μ-S)2(S2CNEt2)2 was determined by x-ray crystallography. The compound crystallizes in space group P21/α with α = 17.540 (3) Å, b = 6.859 (1) Å, c = 17.854 (2) Å, β = 104.67 (1)°, dobsd =1.916 (10) g cm-3, dCalcd = 1.920 g cm-3, and Z = 4. The stereochemistry of the dimer involves syn fusion of the basal edges of two tetragonal pyramids. The equatorial positions of each pyramid are occupied by the two bridging sulfido groups (Sb) and by two sulfur atoms from a S2CNEt2 ligand (S1). The apical position of one pyramid is occupied by a terminal oxo group and that of the other pyramid by a terminal sulfido group. An approximate twofold disorder of the molecule in the crystal precludes accurate determination of the terminal Mo⩵O and Mo⩵S distances and obscures any differences between the two halves of the dimer. In view of the disorder, the least-squares refinement was terminated after convergence of the model with isotropic atoms with.R, = 0.086 for the 1789 data with [Formulla Omitted]The Mo⋯Mo distance is 2.826 (3) Å, the average Mo-Sb distance is 2.317 Å and the average Mo-S1 distance is 2.466 Å. The dihedral angle between the two Mo(Sb)2 planes of the dimer is 149.4°. Mo2OS(M-S2)(S2CNEt2)2 reacted with triphenylphosphine or cyanide to give Mo2O2(μ-S2)(S2CNEt2)2 and either triphenylphosphine sulfide or thiocyanate. This reaction with cyanide is reminiscent of the removal of sulfur from the molybdo enzymes xanthine oxidase and aldehyde oxidase. The possible interrelationships of these reactions is discussed and speculation concerning the function of the cyanide-labile sulfur atom in the enzymes is presented. © 1979, American Chemical Society. All rights reserved.
