Atomically Precise Rigid Copper Nanocluster as an Air‐Stable Photocatalyst for Three‐Component Coupling Reactions

ABSTRACT Copper‐based catalysts exhibit high versatility in organic synthesis. However, their practical utility is often constrained by the limited stability and sensitivity to reaction conditions. In this study, we report a μ 3 – η 1 –S‐bridged nanocluster (NC), Cu 3 (DPPM) 3 S(BF 4 ) (Cu 3 S, DPPM = Bis(diphenylphosphino)methane), that displays exceptional air stability and catalytic robustness due to its strong Cu–S coordination and rigid trigonal symmetry structure. Enabled by its structural stability and excellent photophysical properties, the Cu 3 S NC functions as an efficient photocatalyst for the three‐component coupling reaction of alkyl halides, amines, and alkenes under open‐air, room‐temperature conditions. The catalyst displays high turnover numbers, broad functional group tolerance, and excellent recyclability over multiple cycles. Our findings establish structurally well‐defined low‐nuclearity NCs as versatile and durable catalysts for multicomponent C–N/C–C bond‐forming transformations and reveal structural rigidity as a key design principle for achieving catalytic stability.