Using combinations of oxidants and bases as PCET reactants: thermochemical and practical considerationsThis article was submitted following the PCET conference in October 2011

• Main Authors: Waidmann, Christopher R, Miller, Alexander J. M, Ng, Cheuk-Wa Angela, Scheuermann, Margaret L, Porter, Thomas R, Tronic, Tristan A, Mayer, James M
• Format: Article
• Language: English
• ISSN: 1754-5692; 1754-5706
• DOI: 10.1039/c2ee03300c

Studies in proton-coupled electron transfer (PCET) often require the combination of an outer-sphere oxidant and a base, to remove an electron and a proton. A common problem is the incompatibility of the oxidant and the base, because the former is electron deficient and the latter electron rich. We have tested a variety of reagents and report a number of oxidant/base combinations that are compatible and therefore potentially useful as PCET reagents. A formal bond dissociation free energy (BDFE) for a reagent combination is defined by the redox potential of the oxidant and p K a of the base. This is a formal BDFE because no X-H bond is homolytically cleaved, but it is a very useful way to categorize the H * accepting ability of an oxidant/base PCET pair. Formal BDFEs of stable oxidant/base combinations range from 71 to at least 98 kcal mol −1 . Effects of solvent, concentration, temperature, and counterions on the stability of the oxidant/base combinations are discussed. Extensions to catalysis and related reductant/acid combinations are mentioned. A collection of compatible combinations of one-electron oxidants and organic bases capable of net acceptance of a hydrogen atom has been developed.