Kinetics and DFT Studies of Photoredox Carbon–Carbon Bond Cleavage Reactions by Molecular Vanadium Catalysts under Ambient Conditions

Abstract

Visible light assisted photocatalytic organic reactions have recently received intense attention as a versatile approach to achieve selective chemical transformations, including C–C and several C–X (X = N, O, S) bond formations under mild reaction conditions. The light harvesters in previous reports predominantly comprise ruthenium or iridium photosensitizers. In contrast, selective, photocatalytic aliphatic C–C bond cleavage reactions are scarce. The present study focuses on rationally designing VV oxo complexes as molecular, photoredox catalysts toward the selective activation and cleavage of a C–C bond adjacent to the alcohol group in aliphatic alcoholic substrates. We have employed kinetics measurements and DFT calculations to develop a candidate for the catalytic C–C bond activation reaction that is up to 7 times faster than our original vanadium complex. We have also identified a substrate where the C–C bond cleaves at rates 2.5–17 times faster, depending on the catalyst used. In order to better und...