Bidentate mixed-ligand strategy in dinuclear gold photoredox catalysis

Dinuclear metal complexes have fascinated researchers for decades owing to their unique metal-metal interactions and electronic synergies, which often lead to unconventional reactivity and exceptional catalytic performance. Despite recent efforts in dinuclear gold photoredox catalysis, limited accessibility of structurally diverse architectures has hindered an in-depth understanding of the Au-Au cooperativity, ligand effect, and structure-property relationships. Here, we report a bidentate mixed-ligand strategy for the modular synthesis of unsymmetrical, tricoordinate dinuclear gold complexes featuring both bisphosphine (PP) and bipyridine (NN) ligands. Interestingly, photophysical and computational studies reveal that ligand-to-ligand charge transfer (LLCT), coupled with Au-Au interactions, drives excited-state charge redistribution, enabling inner-sphere single-electron transfer (ISET) for inert C–Br bond activation. These complexes can catalyze three-component carbonylative amidation of unactivated alkyl bromides with amines and CO (balloon) under mild conditions, affording amide products (64 examples) in up to 96% yield. Dinuclear gold complexes have fundamentally expanded catalytic possibilities beyond that of the mononuclear systems. Here the authors report a bidentate mixed-ligand system that can catalyze efficient three-component carbonylative amidation of unactivated alkyl bromides with amines and CO under mild conditions.