Proton-Coupled Electron Transfer Reactivity of Ruthenium Complexes with Separation Between the Proton and Electron Transfer Sites

Abstract

Proton-coupled electron transfer (PCET) events are essential to the function of many processes. In many cases, long-range electron transfers (ET) are coupled to short-range proton transfer (PT) events. Ruthenium bipyridine complexes with a distant carboxylic acid have been synthesized and characterized to study the effect of varying distances between the PT and ET sites on PCET reactions. In reactions with hydrogen atom acceptors, an electron is transferred from the ruthenium center while proton transfer occurs at the distant carboxylic acid. A phenyl spacer can be incorporated into the bipyridine ligand to provide further separation between the ET and PT sites. The results of kinetic experiments allow analysis of the effects of the distance between ET and PT sites on the PCET reactions.