Proton-Coupled O-Atom Transfer in the Oxidation of HSO3- by the Ruthenium Oxo Complex trans-[RuVI(TMC)(O)2]2+ (TMC = 1,4,8,11-Tetramethyl-1,4,8,11-tetraazacyclotetradecane).

We have previously reported that the oxidation of SO32- to SO42- by a trans-dioxoruthenium(VI) complex, [RuVI(TMC)(O)2)]2+ (RuVI; TMC = 1,4,8,11-tetramethyl-1,4,8,11-tetraazcyclotetradecane) in aqueous solutions occurs via an O-atom transfer mechanism. In this work, we have reinvestigated the effects of the pH on the oxidation of SIV by RuVI in more detail in order to obtain kinetic data for the HSO3- pathway. The HSO3- pathway exhibits a deuterium isotope effect of 17.4, which indicates that O-H bond breaking occurs in the rate-limiting step. Density functional theory calculations have been performed that suggest that the oxidation of HSO3- by RuVI may occur via a concerted or stepwise proton-coupled O-atom transfer mechanism.