Syntheses and Structures of Mixed-Metal Sulfido Clusters Containing Trimetallic M₂M‘S₄ (M = Mo, W; M‘ = Pd, Pt) and Tetrametallic Cubane-Type Mo₂Pd₂S₄ Cores

The reaction of the sulfido-bridged dimolybdenum or ditungsten complex [M2S2(μ2-S)2(S2CNEt2)2] (M = Mo (1a), W) with an equimolar amount of [M‘(PPh3)4] (M‘ = Pd, Pt) gave a series of mixed-metal sulfido clusters with a trimetallic M2M‘ core [M‘(PPh3)(μ2-S)2{M(S2CNEt2)}2(μ2-S)2]. The X-ray diffraction study for [Pt(PPh3)(μ2-S)2{W(S2CNEt2)}2(μ2-S)2] (3b) has disclosed the presence of a novel triangular framework, for which the two Pt−W edges are each bridged by one μ2-S ligand and the remaining W−W edge is supported by two μ2-S ligands. Cluster 3b crystallized in the monoclinic system, space group C2/c with a = 13.718(3) Å, b = 12.795(2) Å, c = 43.798(2) Å, β = 95.24(1)°, and Z = 8. Refinement by full-matrix least-squares techniques gave final residuals R = 0.052 and Rw = 0.038. Treatment of [Pd(PPh3)(μ2-S)2{Mo(S2CNEt2)}2(μ2-S)2] with an additional amount of [Pd(PPh3)4] resulted in the formation of the cubane-type mixed-metal sulfido cluster [{Pd(PPh3)}2{Mo(S2CNEt2)}2(μ3-S)4], which was also obtained straightforwardly from the reaction of 1a with 2 equiv of [Pd(PPh3)4].