Electrochemically induced nickel catalysis for oxygenation reactions with water

Nickel has been found in some metalloproteins that execute catalytic aerobic oxygenation reactions in which nickel–dioxygen species are proposed as the key catalytic species. Thus, various nickel–dioxygen complexes have been prepared for biomimetic oxygenation reactions over the past 50 years, but they have often been used stoichiometrically rather than catalytically. The typical inertness of Ni(ii) complexes toward O2 poses a considerable challenge for their application in catalytic aerobic oxygenation. Here, we report a strategy to enable catalytic oxygenation with a simple Ni(ii)–bipyridine complex in which electrochemistry is employed to drive the cascade-activation process for the generation of both active Ni(ii)–peroxo species and O2 for the subsequent oxygenation reaction. We anticipate that this strategy will inspire the development of efficient nickel-catalysed aerobic oxygenations and promote the exploration of transition-metal-based oxidation chemistry in combination with electrochemistry. As Ni(ii) complexes are generally considered inert toward O2, their utilization for catalytic oxygenation reactions is extremely rare. Here, the authors introduce an electrocatalytic method for the oxidation of sulfides based on bipyridine complexes of simple Ni(ii) salts using water as the oxygen source.