Photocatalytic C–H activation and the subtle role of chlorine radical complexation in reactivity

, tetraethylammonium), and RO• are not intermediates. Spectroscopic analyses and kinetics were investigated for C-H activation to identify chlorine radical (Cl•) generation as the rate-limiting step. Density functional theory calculations support the formation of Cl•alcohol adducts when alcohols are present, which can manifest a masked RO• character. This result serves as an important cautionary note for interpretation of radical trapping experiments.