Iron(II) versus osmium(II) oxidation in 1,1′-bis(diorganophosphino)ferrocene–osmium(II) complexes

The compounds [(Cym)OsCl(dxpf)](PF6), Cym=p-cymene and dxpf: 1,1′-bis(diphenylphosphino)ferrocene (dppf), 1,1′-bis(diethylphosphino)ferrocene (depf) or 1,1′-bis(diisopropylphosphino)ferrocene (dippf), were synthesized and characterized by NMR (1H, 31P) and, in the case of [(Cym)OsCl(dppf)](PF6), by X-ray structure analysis of the acetonitrile solvate. EPR and UV–vis spectroelectrochemistry indicate the formation of an osmium(II)–ferrocenium species on reversible one-electron oxidation. The second oxidation and the reduction are electrochemically irreversible.