Photodehydrogenation of alcohols catalysed by a single ruthenium N-Heterocyclic carbene complex

• A ruthenium complex catalyses the photodehydrogenation of benzylic alcohols in water to render the carboxylate salts and two molecules of H 2 . • A standalone ruthenium complex plays a dual task harvesting visible light and being responsible for the bond breaking/forming event. • Blue visible light enhances the hydricity of the Ru-H bond facilitating the generation and release of H 2 under mild conditions. • The presence of an NHC ligand bearing methyl and pyrenylmethylene substituents at the azole ring are key for the observed catalytic performance. • This molecular complex is postulated as a competent contender for future hydrogen storage technologies. The transition metal catalyzed dehydrogenation of alcohols to carboxylate salts and H 2 is an attractive tool due to their potential use as LOHCs (Liquid Organic Hydrogen Carriers). Still, most current methods encompass harsh conditions and two steps synthesis. Herein, we describe an efficient ruthenium(II) catalyzed hydrogen production from benzylic alcohols to the corresponding carboxylate derivatives assisted by visible light. Our photocatalytic system comprises a standalone N-heterocyclic carbene based piano stool ruthenium complex playing a dual role, harvesting visible-light and enabling H 2 generation under mild conditions in aqueous media.