ELECTROCHEMICAL AND ESR KINETICS STUDIES OF ELECTRON TRANSFER IN THE SYSTEM BIS(η6-ARENE)CHROMIUM(0)/BIS(η6-ARENE)CHROMIUM(I)

Article abstract of DOI:10.1016/S0022-328X(00)85762-9

The self-exchange rates and activation parameters in the (η⁶-arene2Cr⁰/(η⁶-arene)2Cr^I systems (where arene = toluene, benzene, methoxylbenzene, biphenyl, ethylbenzoate and chlorobenzene) have been measured by the ESR line broadening technique in DMSO solvent.The one-electron reduction was investigated by cyclic voltammetry for the series of substituted complexes of (η⁶-arene)2Cr^I.A linear correlation was obtained between the measured E_1/2 values and the sum of Hammett parameters, Σ?_m.For a series of solvents, a linear relationship between log k (the exchange rate constant of (biph)2Cr^0/+1) and (1/n²-1/D_s) where n² and D_s are the optical and static dielectric constants of the solvent medium, respectively, has been observed.This linearity is predicted by Marcus treatment for outer-sphere electron transfer process.A correlation of the oxidation stability of sandwich compounds with their gas-phase ionization potentials is evident from a linear relationship between the oxidation half-potentials E_1/2 (or sum of Hammett Σ?_m values) and the gas-phase ionization potentials.