Synthesis of metal dithiolene complexes by Si–S bond cleavage of a bis(silanylsulfanyl)alkene

A new method for the synthesis of metal dithiolenes with alkyl-substituted chelate rings has been investigated. The utility of the protected ene-1,2-dithiolate 3,4-bis-triisopropylsilanyl-sulfanyl-hex-3-ene as a precursor in reactions with metal halide and oxyhalide complexes was examined. Reaction conditions involve a 2:1 or 3:1 mol ratio of reactants in acetonitrile/THF or toluene at 50–80 °C for 24–36 h. Complex formation was observed as a result of Si–S bond cleavage by bound or free halide and oxo ligands. Members of four major structural families of dithiolene complexes were prepared in ca. 25–70% yields, including planar [Ni(S2C2Et2)2], square pyramidal [MI(S2C2Et2)2] (M = Co, Fe), [Fe(py)(S2C2Et2)2]1−, and [ReO(S2C2Et2)2]1−, centrosymmetric [M2(S2C2Et2)4]2− (M = Co, Mn), [M(S2C2Et2)3]1− (M = V, Nb), and trigonal prismatic [M(S2C2Et2)3] (M = Mo, W). Seven X-ray structure proofs are provided. It is concluded that the method is feasible and potentially extendable to other ring substituents, whose primary effects are on solubility and modulation of redox potentials.