SYNTHESES AND STRUCTURES OF MIXED-METAL SULFIDO CLUSTERS CONTAINING TRIMETALLIC M2M'S-4 (M = MO, W, M' = PD, PT) AND TETRAMETALLIC CUBANE-TYPE MO2PD2S4 CORES

The reaction of the sulfide-bridged dimolybdenum or ditungsten complex [M2S2(mu(2)-S)(2)(S2CNEt2)(2)] (M = Mo (1a), W) with an equimolar amo unt of [M'(PPh3)(4)] (M' - Pd, Pt) gave a series of mixed-metal sulfid e clusters with a trimetallic M2M' core [M'(PPh3)(mu(2)-S)(2){M(S2CNEt 2)}(2)(mu 2-S)(2)]. The X-ray diffraction study for [Pt(PPh3)(mu(2)- s )(2){W(S2CNEt2)}(2)(mu(2)-S)(2)] (3b) has disclosed the presence of a novel triangular framework, for which the two Pt-W edges are each brid ged by one mu(2)-S ligand and the remaining W-W edge is supported by t wo mu(2)-S ligands. Cluster 3b crystallized in the monoclinic system, space group C2/c with a = 13.718(3) Angstrom, b = 12.795(2) Angstrom, c = 43.798(2) Angstrom, beta = 95.24(1)degrees, and Z = 8. Refinement by full-matrix least-squares techniques gave final residuals R = 0.052 and R-w = 0.038. Treatment of [Pd(PPh3)(mu(2)-S)(2){Mo(S2CNEt2)}(2)(m u(2)-S)(2)] with an additional amount of [Pd(PPh3)(4)] resulted ih the formation of the cubane-type mixed-metal sulfide cluster [{Pd(PPh3)}( 2){Mo(S2CNEt2)}(2)(mu(3)-S)(4)], which was also obtained straightforwa rdly from the reaction of 1a with 2 equiv of [Pd(PPh3)(4)].