Visible-Light-Promoted Iridium(III)-Catalyzed Acceptorless Dehydrogenation of N-Heterocycles at Room Temperature

An effective visible-light-promoted iridium(III)-catalyzed hydrogen production from N-heterocycles is described. A single iridium complex constitutes the photocatalytic system playing a dual task, harvesting visible-light and facilitating C-H cleavage and H-2 formation at room temperature and without additives. The presence of a chelating C-N ligand combining a mesoionic carbene ligand along with an amido functionality in the Ir-III complex is essential to attain the photocatalytic transformation. Furthermore, the Ir-III complex is also an efficient catalyst for the thermal reverse process under mild conditions, positioning itself as a proficient candidate for liquid organic hydrogen carrier technologies (LOHCs). Mechanistic studies support a light-induced formation of H-2 from the Ir-H intermediate as the operating mode of the iridium complex.