Thermodynamic and kinetic characteristics of intermediates of electrode reactions. Comparative laser photoemission study of the kinetics of electron transfer for certain alkylaryl and alkylhalide radicals

Abstract

Using the laser photoemission technique, a comparative study of thermodynamic and energy characteristics of electron transfer (ET) is carried out for a number of alkylaryl intermediates (IM) (benzyl, benzhydryl radicals) and alkyl halides (chloromethyl and dichloromethyl radicals). It is found that the standard free energies of activation of radicals under study are 0.34–0.38 eV and the preexpoential factors are between 109 and 1010s−1 and weakly depend on the solution nature. The reorganization energies of the medium for these IM are estimated in terms of the classical Marcus theory. The results are compared with the literature data on the dissociative ET in monohalogenomethanes CH3Hal/CH3Hal−·, polychloromethanes CHnHal4 − n/CHnHal4−n−·, and some other systems. Possible reasons for the different probabilities of observing reversible ET for IM under study are discussed.