A photoactive nickel complex provides evidence for a general Ni(I)/Ni(III) paradigm in cross-coupling catalysis

Advances in nickel catalysis have significantly broadened the synthetic chemists' toolbox, particularly through methodologies leveraging paramagnetic nickel species via photoredox catalysis or electrochemistry. Nonetheless, the mechanisms of these transformations remain poorly understood. In a pursuit to expand the scope of C(sp2)–heteroatom couplings by modulating the electronic properties of donor-acceptor ligands, we identified a photoactive nickel complex capable of catalyzing C(sp2)–C(sp3) cross-couplings between aryl halides and benzyltrifluoroborate salts without involving photoredox reactivity. Mechanistic investigations provided compelling evidence that an unprecedented direct transmetalation between a NiI intermediate and the organoboron species serves as pivotal catalytic step. More generally, these findings suggest that photo/electrochemically-mediated nickel-catalyzed C(sp2)–heteroatom and C(sp2)–C(sp3) bond formations can operate via similar Ni(I)/Ni(III) manifolds.