Bimolecular photoinduced electron transfer in the Marcus inverted region involving the [Re(CO) 3(4-phenylpyridine) 3] + metal-to-ligand charge transfer excited state, amines and their corresponding radical products

Abstract

Bimolecular electron transfer quenching of the metal-to-ligand charge transfer (MLCT) excited state of Re(CO) 3 (4-phenylpyridine) 3 (F 3CSO 3) by amines was studied in acetonitrile at room temperature. The quenching rate constants ( κ q) vary from 1.8 × 10 7 to 2.5 × 10 10 M −1s −1 (diffusion limit). Moreover, the radical recombination reaction (back electron transfer) was also studied by flash photolysis. The back electron transfer rate constants range from 2.8 × 10 5 to 7.0 × 10 9 M −1s −1, lying below the diffusion-controlled limit. The rate constants show an inverse dependence on the driving force in the inverted region. All the data points can be fitted using a semiclassical model.