Three-state model for two-electron transfer reactions

Much of electron transfer based catalysis relies upon multielectron rather than single-electron transfer processes. If the multielectron events proceed through stable one-electron intermediates, conventional theory describes the events. However, when an unstable one-electron intermediate plays a role, when a stable intermediate lives for a brief period of time, or when concerted multielectron events occur, the electronic coupling and free energy dependence of the rate is distinct from that arising in one-electron theories. We describe several new features that can arise in multielectron processes, predict their experimental signature, and show how these ideas can be applied to specific experimental systems.