Visible-light assisted dehydrogenation of benzylamines catalysed by a standalone ruthenium complex.

The dehydrogenation of benzyl amines to produce the corresponding nitriles and H2 is an appealing strategy due to their application in hydrogen storage technologies. On the other hand, a wide range of current synthetic strategies to produce nitriles require a stepwise synthesis and severe reaction conditions. Here, we report an efficient visible-light promoted ruthenium(II) catalyzed hydrogen production from benzylic amines to the corresponding nitrile derivatives at room temperature and without additives. Our photocatalytic system comprises a single anionic 2-pyridonate based piano stool ruthenium precatalyst playing a dual role, harvesting visible-light and enabling H2 generation in methanol. Mechanistic studies support pre-dissociation of the p-cymene ligand after light irradiation and formation of a solvato derivative that further enhances the catalytic activity towards nitrile formation.