A molecular mediator for reductive concerted proton-electron transfers via electrocatalysis

Delivering protons with electrons Many chemical reactions involve concurrent transfer of a proton and an electron. In electrochemical synthesis, this mechanism could prove useful in lowering the energy necessary for cathodic electron transfer alone, but it is hindered by competing direct coupling of the protons and electrons to make hydrogen instead. Chalkley et al. now report a molecular mediator consisting of a dimethylaniline base tethered to a cobaltocenium electron acceptor. This construct can deliver both a proton and an electron to a substrate from an acid and a cathode while skirting the hydrogen pathway. Science , this issue p. 850