Mixed chloride–phosphine complexes of the dirhenium core. Part 11. Reactions of [Re 2Cl 8] 2− with secondary phosphines, PCy 2H and PPh 2H

Abstract

The reaction between the dirhenium(III,III) anion, [Re 2Cl 8] 2−, and the secondary phosphine, PCy 2H, yields a mixture of products as a result of disproportionation, namely, a dirhenium(II,III) chloride–phosphine complex 1,3,6-Re 2Cl 5(PCy 2H) 3 ( 1) and a dirhenium(IV) face-sharing bioctahedral compound with bridging phosphido groups, [Bu n 4N][Re 2(μ-PCy 2) 3Cl 6] ( 2). The diphenylphosphine analogue of 2, [Bu n 4N][Re 2(μ-PPh 2) 3Cl 6] ( 3) has been similarly prepared from the reaction of [Re 2Cl 8] 2− with PPh 2H. An interesting dirhenium(III,III) complex, [Bu n 4N] 2[Re 2(μ-PPh 2) 2(PPh 2H) 2Cl 6] ( 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.