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(dip henylphosphino)ferrocene (dppf), 1, 1'-bis(diethylphosphino)ferrocene (depf ) or 1,1'-bis(diisopropylphosphino)ferrocene (dippf), were synthesized and characterized by NMR (H-1, P-31) and, in the case of [(Cym)OsCl(dppf](PF6), by X-ray structure analysis of the acetonitrile solvate. EPR and UV-vis sp ectroelectrochemistry indicate the formation of an osmium(II)-ferrocenium s pecies on reversible one-electron oxidation. The second oxidation and the r eduction are electrochemically irreversible. (C) 2001 Elsevier Science B.V. All rights reserved.