NOVEL BIMETALLIC SULFUR CLUSTER - CRYSTAL AND MOLECULAR-STRUCTURE OF A DIMER OF BIS[METHYLDIPHENYLPHOSPHINESILVER]TETRATHIOTUNGSTEN, [(C6H5)2PCH3]4AG4W2S8

The title compound, I, is formed from [(C6H5)2PCH3]4Ag2WS4 (II) with loss of phosphine in polar solvents. The crystal and molecular structure of 1 has been determined from three-dimensional X-ray data collected by counter methods. The molecular compound I crystallizes in the monoclinic space group P21/n with Z = 2 and cell dimensions a = 11.901 (4) Å, b = 12.233 (5) Å, c = 20.375 (10) Å, β = 92.25 (3)°. The observed and calculated densities are 2.04 and 2.08 g/cm3, respectively. The structure has been refined to a final R factor on F of 0.049 for 2096 observed reflections. The structure of I consists of a 12-atom cluster containing four silver atoms, two tungsten atoms, and six sulfur atoms; the cluster possesses a crystallographic center of symmetry. Based on 31P NMR data for II and the structures of the closely related [(C6H5)2PCH3]2Au2MS4 compounds (M = Mo, W), a mechanism for the formation of I from II is proposed. Copyright © 1979, American Chemical Society. All rights reserved.