Springboard Role for Iridium Photocatalyst: Theoretical Insight of C(sp3)−N Cross‐Coupling by Photoredox‐Mediated Iridium/Copper Dual Catalysis versus Single‐Copper Catalysis

Abstract Photoredox‐mediated dual metal catalysis has been considered as a more efficient method for cross‐coupling reactions than single metal catalysis, however, the nature of the significant difference is still unclear. In this work, theoretical research into the decarboxylative C(sp 3 )−N couplings by Ir III /Cu I metallaphotoredox catalysis has been performed by density functional theory (DFT) calculations. A cooperative catalysis mechanism merging the photocatalytic cycle (Ir III −*Ir III −Ir II −Ir III ) and the copper catalytic cycle (Cu I −Cu II −Cu III −Cu I ) has more advantages. For the dual catalysis, the photocatalyst plays a “springboard” role in matching better the energy levels of Ir III /Cu I and Cu I /substrates, which could improve the single electron transfer rate. Moreover, exogenous bases could adjust the proton transfer process and decrease the energy barrier of the rate‐determining step to achieve the regioselective monofunctionalization. These theoretical insights could contribute to a deeper understanding of the nature of the photocatalytic decarboxylation reaction and to further developing new cross‐coupling reactions.