Mixed chloride–phosphine complexes of the dirhenium core. Part 11. Reactions of [Re2Cl8]2− with secondary phosphines, PCy2H and PPh2H

The reaction between the dirhenium(III,III) anion, [Re2Cl8]2−, and the secondary phosphine, PCy2H, yields a mixture of products as a result of disproportionation, namely, a dirhenium(II,III) chloride–phosphine complex 1,3,6-Re2Cl5(PCy2H)3 (1) and a dirhenium(IV) face-sharing bioctahedral compound with bridging phosphido groups, [Bun 4N][Re2(μ-PCy2)3Cl6] (2). The diphenylphosphine analogue of 2, [Bun 4N][Re2(μ-PPh2)3Cl6] (3) has been similarly prepared from the reaction of [Re2Cl8]2− with PPh2H. An interesting dirhenium(III,III) complex, [Bun 4N]2[Re2(μ-PPh2)2(PPh2H)2Cl6] (4) having both neutral terminal phosphines and anionic phosphido bridges, has also been isolated as an intermediate in the latter system. Crystal structures of 1–4 have been determined by X-ray crystallography. The compounds were also characterized by cyclic voltammetry, IR and 31P NMR spectroscopy.