Electrocatalytic C–H Phosphorylation through Nickel(III/IV/II) Catalysis

C–H phosphorylation was achieved by Earth-abundant nickel cata- lysts with waste-free electricity as the redox surrogate. The robust nickela-electrooxidative C–H activation of arenes, heteroarenes, and olefins with diverse phosphonating reagents successfully deliv- ered arylphosphonates, phenylphosphine oxides, and diazaphos- pholidine oxides of relevance to bioactive compounds and materials. The guanidine-assisted electrooxidative C–P formation avoided chemical oxidants with molecular hydrogen as the sole by- product. Catalytically relevant nickel(II) and nickel(III) intermediates were isolated and fully characterized by X-ray diffraction analysis. Catalytically relevant nickel complexes were observed by in oper- ando high-resolution electrospray ionization mass spectrometry (HR-ESI-MS) monitoring. Cyclic voltammetry analysis and density functional theory (DFT) calculations provided strong evidence for a nickel(III/IV/II) manifold.