Suppressing the active site-blocking impact of ligands of Ni6(SR)12 clusters with the assistance of NH3 on catalytic hydrogenation of nitriles

Abstract

Atomically precise metal clusters stabilized by organic ligands have attracted extensive interest, and these monodisperse clusters have particular potential for providing insights into puzzling areas of heterogeneous catalysis such as inherent size polydispersity. In many traditional catalytic reactions, however, the reactivity of metal clusters is frequently found to be passivated, where the active sites on the surface metal atoms are blocked by the ligand molecules. Therefore, of particular interest are studies that involve triggering the catalytic ability of metal clusters, with no need to remove any ligands, via thermal treatments that usually destroy their atomically precise structures. Herein, with the determination of the structure of Ni₆(SR)₁₂ (where SR denotes thiolate), where Ni atoms are fully coordinated with the thiolate molecules, the catalytic activity of Ni₆(SR)₁₂ for nitriles hydrogenation toward primary amines could be significantly enhanced with the assistance of NH₃ molecules that positively suppress the ligand-shielding effect.