Simultaneous in-situ electron spin resonance and voltammetric studies in high resistance solvents at low temperatures using a newly designed small volume electrolysis cell

Abstract

A newly designed microcell enabling 0.2 cm3 or smaller volumes of sample to be examined simultaneously by controlled potential electrolysis, voltammetric and electron spin resonance techniques in high resistance media at low temperatures is described. In-situ electrochemical oxidation in dichloromethane of either mer or fac-[Cr(CO)3P3] (P = phosphine ligand) in this cell, which is contained within the resonant cavity of an ESR spectrometer, produces ESR spectra consistent with the formation of the seventeen electron mer-[Cr(CO)3P3]+ isomer. Rates of isomerization fac-[Cr(CO)3P3]+ → mer-[Cr(CO)3P3]+ can be calculated from cyclic voltammetric experiments and the time dependence of ESR spectra are consistent with this data, assuming that fac-[Cr(CO)3P3]+ is ESR insensitive, compared to the mer+ isomer. Simultaneous use of ESR and electrochemical techniques in a cell with these characteristics should facilitate mechanistic studies of electron transfer reactions in high resistance media.