Quantum Effects for Electron-Transfer Reactions in the “Inverted Region”

Quantum effects in outer-sphere electron transfer reactions in the inverted region are considered. The results of quantum, “semiclassical, and classical calculations on model systems are presented. A series of highly exothermic reactions of tris(bipyridyl) complexes involving electronically excited reactants is discussed with regard to the possible importance of quantum effects and of alternate reaction pathways in understanding the failure of the series of reactions to exhibit pronounced “inverted” behavior. Electronically excited products or alternate atom-transfer mechanisms provide possible explanations for the large discrepancy.