Proton-coupled intervalence charge transfer: concerted processes

The kinetics of proton-induced intervalence charge transfer (IVCT) may be measured electrochemically by generating one of the members of the IVCT couple in situ and following its conversion by means of the electrochemical signature of the other member of the couple. In the case of the diiron complex taken as an example, the reaction kinetics analysis, including the H/D isotope effect, clearly points to the prevalence of the concerted proton-intervalence charge transfer pathway over the stepwise pathways. A route is thus open toward systematic kinetic studies of proton-induced IVCT aiming at uncovering the main reactivity parameters and the factors that control the occurrence of concerted versus stepwise pathways.