Electrochemistry of organometallic compounds I. Cyclic voltammetry of organocobaloximes in aqueous acid solutions

Abstract

This paper presents a systematic investigation on effects of the nature of the organic axial ligand on the primary electrochemical oxidation steps of organoaquobis(dimethylglyoximato)cobalt(III). Evidence is presented to support a one electron reversible process, yielding a cobalt(III) compound attached to the organic radical. Studies of p-substituted benzyl and phenyl derivatives support further the proposed process. The following step is a pseudo-first order irreversible dissociation of the oxidized species, yielding the trans-Co(DH)2(H2O)+ and the organic radical that can be further oxidized at the electrode. Linear free energy correlations obtained between E1/2 and Taft or Hammett parameters, depending on the nature of the organic substituent in axial position, strongly favor that Co-alkyl(aryl) bonding electrons are involved in the electron transfer.