Ion pairing and electron transfer

Several scenarios are considered for the effect of electrolytes, specifical ly for ion pairing, on the rates of electron transfer reactions: (i) electr on transfer followed by ion transfer, (ii) ion-pair dissociation followed b y electron transfer, or (iii) ion transfer accompanying the electron transf er. The latter may involve fast or slow (diffusive) ionic motion. A distinc tion is made between ion reorganization (case (iii)) and the formation of r eal chemical intermediates. The ion pairs themselves may be tight (contact) or loose (solvent separated). The discussion is illustrated with an exampl e in the literature. Differences in degree in behavior of intramolecular an d intermolecular electron transfer, due to differences in extent of ionic m otion, are noted.