Exploring mechanistic preferences and influencing factors in acceptorless dehydrogenation reactions catalyzed by an Ir(iii)-dipyridylamine complex: A DFT study

Acceptorless dehydrogenation reactions play a pivotal role in homogeneous catalysis, with extensive applications in organic synthesis and industrial processes. Metal-ligand cooperative catalysis is crucial for enhancing reaction efficiency and selectivity. However, understanding its mechanistic pathways and identifying factors influencing catalytic performance remain challenging. In this study, density functional theory (DFT) is employed to elucidate the mechanistic selectivity of Ir(III)-bis(pyridyl)amine complexes in acceptorless dehydrogenation reactions. We specifically investigate the selectivity between pyridine nitrogen and bridging nitrogen as proton acceptor sites during the dehydrogenation process. The results indicate that the pyridine nitrogen site is preferentially chosen as the proton acceptor due to its stronger basicity and lower deformation energy. Additionally, theoretical investigations of catalytic activity across different metals in the same group reveal that early transition metals significantly influence the basicity of the pyridine nitrogen, thereby affecting catalytic activity. Our findings elucidate the unique mechanistic selectivity of bis(pyridyl)amine-based catalysts and identify critical factors influencing this selectivity, providing essential theoretical guidance for the design of more efficient catalysts in future research.