Controlled Photocatalytic Hydrocarbon Oxidation by Uranyl Complexes

Abstract Controlled, photocatalytic C−H bond activations are key reactions in the toolkits of the modern synthetic chemist. While it is known that the uranyl(VI) ion, [U VI O 2 ] 2+ , the environmentally dominant form of uranium, is photoactive, most literature examines its luminescent properties, neglecting its potential synthetic utility for photocatalytic C−H bond cleavage. Here, we synthesise and fully characterise an air‐stable and hydrocarbon‐soluble uranyl phenanthroline complex, [U VI O 2 (NO 3 ) 2 (Ph 2 phen)], U Ph2phen , and demonstrate that it can catalytically abstract hydrogen atoms from a variety of organic substrates under visible light irradiation. We show that the commercially available parent complex, uranyl nitrate ([U VI O 2 (NO 3 ) 2 (OH 2 ) 2 ]⋅4H 2 O; U NO3 ), is also competent, but from electronic spectroscopy we attribute the higher rates and selectivity of U Ph2phen to ligand‐mediated electronic effects. Ketones are selectively formed over other oxygenated products (alcohols, etc .), and the catalytic oxidation of substrates containing a benzylic C−H position is particularly improved for U Ph2phen . We also show uranyl‐mediated photocatalytic C−C bond cleavage in a model lignin compound for the first time.