A Non-Heme Iron Photocatalyst for Light-Driven Aerobic Oxidation of Methanol.

Non-heme (L)FeIII and (L)FeIII -O-FeIII (L) complexes (L=1,1-di(pyridin-2-yl)-N,N-bis(pyridin-2-ylmethyl)ethan-1-amine) underwent reduction under irradiation to the FeII state with concomitant oxidation of methanol to methanal, without the need for a secondary photosensitizer. Spectroscopic and DFT studies support a mechanism in which irradiation results in charge-transfer excitation of a FeIII -μ-O-FeIII complex to generate [(L)FeIV =O]2+ (observed transiently during irradiation in acetonitrile), and an equivalent of (L)FeII . Under aerobic conditions, irradiation accelerates reoxidation from the FeII to the FeIII state with O2 , thus closing the cycle of methanol oxidation to methanal.