MOLYBDENUM COMPLEXES OF ALIPHATIC THIOLS - STRUCTURES OF SYN AND ANTI ISOMERS OF DI-MU-SULFIDO-BIS(SULFIDO-1,2-DIMERCAPTOETHANATOMOLYBDATE(V)) ANION, [MO2S4(S2C2H4)2]2-

The structures of the tetraethylammonium salts of the syn and anti isomers of [Mo2S4(dme)2]2- (where dme is the dianion of 1,2-dimercaptoethane) have been determined by x-ray crystallography. The syn isomer crystallizes in space group P21/c with [formula omitted]. The calculated and observed densities are 1.537 and 1.528 (4) g cm-3, respectively. Full-matrix least-squares refinement of the structure using the 3258 data with [formula omitted]. The anti isomer crystallizes in space group P21/n with [formula omitted]. The calculated and observed densities are 1.576 and 1.563 (4) g cm-3, respectively. Full-matrix least-squares refinement of the structure using the 1401 data with [formula omitted] and R2=0.049. The inner coordination environments of the molybdenum atoms of the two isomeric binuclear anions are quite similar. Each molybdenum atom is ligated by five sulfur atoms in approximately tetragonal-pyramidal coordination geometry. The axial position of each pyramid is occupied by a terminal sulfido group (St); the equatorial positions are occupied by bridging sulfido groups (Sb) and the sulfur atoms from the dme ligands (S1). The geometries of the four-membered Mo2S2 rings of the two isomers are different. The dihedral angle between the two MoS2 planes of the syn isomer is 146.9 (3)° whereas the Mo2S2 ring of the anti isomer is required to be planar by the space group. The Mo⋯Mo distances in syn- and anti-[Mo2S4(dme)2]2- are nearly identical, 2.863 (2) and 2.878 (2) Å, respectively. The average Mo-Sb-Mo angles are 76.2 and 76.7°, respectively. The average Sb-Mo-Sb angle in the syn isomer is 99.9°, and the Sb-Mo-Sb angle in the anti isomer is 103.4°. © 1978, American Chemical Society. All rights reserved.