Alkyne Dihydroboration via In Situ-Formed Nickel Cluster Catalysis: Reordering Group Addition by Multinuclear Nature

Understanding the roles and dynamic evolution of active species represents a crucial yet challenging frontier in catalysis research, particularly in systems involving in situ-formed nanoclusters. Owing to the multimetallic nature of soluble nanoclusters, elucidating their distinct catalytic mechanisms, which differ fundamentally from those of conventional homogeneous molecular catalysts or heterogeneous surfaces, has emerged as a critical scientific priority, though this field remains largely unexplored. Herein, we demonstrate a nickel-catalytic system that achieves the regioselective double hydroboration of unsymmetrical internal alkynes with pinacolborane (HBpin), enabling efficient synthesis of sterically congested quaternary 1,1-diboryl alkanes. Mechanistic studies reveal that the catalytic activity originates from in situ-generated Ni nanoclusters, which uniquely activate multiple HBpin simultaneously and enable geminal (H, H) and (B, B) addition to alkynes. This proposed gem-addition mechanism diverges fundamentally from classical sequential double hydroboration pathways mediated by monometallic centers, highlighting the advantages of polynuclear architectures in unlocking unprecedented reactivity and catalytic pathways.