Synthesis, structure, and properties of sulfido-bridged dinuclear tungsten(V) complex of dithiolene, (Pr4N)2[W2(μ-S)2{S2C2(CO2Et)2}4]

The reaction of tetrathiotungstate (WS42−) with diethyl acetylenedicarboxylate, EtO2CCCCO2Et, in the presence of dinuclear Pt(III) complex [Pt2Cl2(5-mpyt)4] (5-mpyt=5-methylpyridine-2-thiolato) as an oxidant gave a sulfido-bridged dinuclear tungsten(V) complex of dithiolene, (Pr4N)2[W2(μ-S)2{S2C2(CO2Et)2}4] (1). The absence of an appropriate oxidant in the reaction system afforded tris(dithiolene) complex (Pr4N)2[W{S2C2(CO2Et)2}3] (2). The complex 1 was characterized structurally and spectroscopically. The complex anion in 1 has an edge-shared bioctahedral structure with two bridging sulfide ions, WW distance being 2.9425(7) Å. The fluxionality of the dithiolene ligand was observed by 1H-NMR even at −50°C for 1.