Spectroelectrochemical studies of nickel(I) complexes: One-electron reduction of nickel(II) complexes of dithiocarbamate and phosphine ligands [Ni(R2NCS2)x(Ph2PCH 2CH2PPh2)2-x]2-x (x = 0, 1, 2)

Article abstract of DOI:10.1021/ic00133a054

The electrochemical generation and stability of nickel(I) complexes of the type [Ni(R₂NCS₂)_x(dpe)_2-x]^1-x (x = 0, 1, 2; dpe = Ph₂PCH₂CH₂PPh₂) have been investigated with use of the methods of electron spin resonance (ESR) spectroscopy and cyclic voltammetry. Reduction of the bis(dithiocarbamato) complexes Ni^II(R₂NCS₂)₂ at a Pt electrode in dichloromethane solution yields an initial planar nickel(I) species, which interconverts to a new nickel(I) species with reversed g values. In contrast Ni(dpe)₂²⁺ undergoes two closely spaced reductions, the first of which corresponds to a nickel(I) complex with four equivalent phosphorus ligands bound to the metal. The mixed-ligand complex [Ni^II(R₂NCS₂)(dpe)]PF₆ may be reduced to a nickel(I) species with two equivalent phosphorus ligands bound to the metal. This species undergoes a series of further reactions, resulting in an overall disproportionation to Ni^II(R₂NCS₂)₂ and Ni⁰(dpe)₂. The kinetics and mechanism of this reaction have been investigated with use of ESR spectra and cyclic voltammetry. The nickel(I) complexes [Ni(R₂NCS₂)₂]^- can also be generated by γ irradiation of frozen solutions of Ni(R₂NCS₂)₂, and these have been characterized with use of ESR spectroscopy.