A theory for nonadiabatic electrochemical electron-transfer reactions involving the breaking of a bond

A simple model for bond-breaking electrochemical electron-transfer reactions is considered in the nonadiabatic limit, and an explicit expression for the rate constant is derived from first-order perturbation theory. Explicit model calculations are performed for the quantum regime. Tunneling effects are important, and the energy of activation is considerably smaller than predicted by classical theories. The energy-resolved rate exhibits features that are quite different from those of outer-sphere reactions.