Electrochemistry of the nickel(II) tris(2-diphenylphosphinoethyl)phosphine halide cations and an x-ray crystallographic structure of Ni(eta sup 4 -P3P')Br PF6.1/2MeCN.H2O

The electrochemical reactions of the nickel(II) tris(2-diphenylphosphinoethyl)phosphine (P3P') halide cations in acetonitrile and dichloromethane were investigated. It was found that the cations reduce to the nickel(0) Ni eta(sup 4)-P3P' X (sup -) species. The bromo and iodo complexes lose halides and form a P3P'-bridged nickel(0) dimer after reduction. All, however, are 'irreversibly oxidized to the analogous nickel(III) series.'