Proton-Coupled Electron Transfer at a [Co-OHx]z Unit in Aqueous Media: Evidence for a Concerted Mechanism
The proton-coupled electron transfer (PCET) chemistry associated with the [Co-OH]2+/[Co-OH2]2+ redox couple for [Co(PY5)(OH2)]2+ (1; PY5 = 2,6-(bis(bis-2-pyridyl)-methoxymethane)-pyridine) and [CoII(pz4depy)(OH2)]2+ (2; pz4depy = 2,6-bis(1,1-di(1H-pyrazol-1-yl)ethyl)pyridine) is reported. It is found that the couple is acutely sensitive to the geometry of the axially ligated group in addition to the electronic-donating/-withdrawing character of the ligand. Interrogation of the electron-transfer kinetics by electrochemical methods also shows for the first time that the interconversion of [CoIII-OH]2+ and [CoII-OH2]2+ proceeds through a concerted pathway in favour of energetically unfavourable stepwise electron-transfer or proton-transfer reaction steps.
Wasylenko, Derek J.; Tatlock, Heidi M.; Bhandari, Luvdeep S.; Gardinier, James R.; and Berlinguette, Curtis P., "Proton-Coupled Electron Transfer at a [Co-OHx]z Unit in Aqueous Media: Evidence for a Concerted Mechanism" (2013). Chemistry Faculty Research and Publications. 251.