Photochemical Arylation Reactions Mediated by a Terpyridine Cobalt Complex

The complex [Co II (4′‐MeO‐tpy) 2 ](PF 6 ) 2 (4′‐MeO‐tpy = 4′‐methoxy‐2,2′:6′,2″‐terpyridine) effectively mediates the visible‐light‐driven arylation of pyrroles, 1,3,5‐trimethoxybenzene, and bis(pinacolato)diborane (B 2 Pin 2 ). Mechanistic studies suggest the reaction likely proceeds via a halogen atom transfer mechanism facilitated by an α ‐aminyl radical. This work highlights the potential of optimizing the ligand framework and reaction conditions to advance the application of earth‐abundant transition metal complexes in photoredox catalysis.