Contribution of ionic effects to electron transfer reactions

Abstract

This paper reports an initial effort to combine the theory of ionic conductivity, due to Friedman, with the theory of simple outer sphere electron transfer reactions. In this work the ions, which do not participate in the electron transfer transitions, are considered individually. The solvent is considered, as elsewhere, as a dielectric continuum. The calculations are carried out for extreme ionic dilution, a Debye–Hückel limit. The purpose of this work is to attempt to provide a more detailed account of the effect of ions present in the solution on the reaction rate. The effect which arises manifests itself through the reaction rate constant expression. Specifically, we find that as a result of the interaction between the electron transfer system and the ions in solution, transport coefficients associated with ionic mobilities in solution appear in the rate constant expression. The nature of the ionic effect is similar to the effect found when one considers either damping of the electron transfer transition state or damping of the energy states of the polarization modes of the dielectric continuum.