Ligand-Modulated Synthesis of High-Nuclearity Copper Nanoclusters Enables Photocatalytic Functionalization of C–Cl and C–F Bonds

Abstract The controlled synthesis of high-nuclearity copper nanoclusters (Cu NCs) remains a long-standing challenge due to the intrinsic lability, rapid redox cycling, and strong aggregation tendencies of Cu(I)–NCs. We introduce a BINAP (2,2′-bis(diphenylphosphino)-1,1′-binaphthyl)-assisted, thiolate-driven strategy that enables the ultrafast assembly of a high-nuclearity Cu NCs [Cu63(TBBT)44(CH3COOCH3)2(CH3CN)4(CH3OH)H14]3+ (Cu63). Notably, BINAP functions as a transient chelating ligand that stabilizes Cu(I), moderates reduction kinetics, and suppresses uncontrolled thiolate polymerization. The resulting Cu63 structure features a 12-atom Cu core capped by a Cu51(TBBT)44 (TBBT: 4-tert-butylbenzenethiol) shell containing well-defined surface vacancy defects that modulate ligand arrangement and electronic structure. Cu63 exhibits a broad absorption tail that extends continuously into the visible region, air stability, and favorable excited-state redox properties. These synergistic properties render the high-nuclearity Cu-cluster an effective photoredox catalyst for the activation of unactivated aryl chlorides and fluorides under mild conditions.