Boosting Metal Nanocluster Catalysis With Functional Ligands

ABSTRACT Ligand‐protected metal nanoclusters have garnered considerable attention in recent years as a class of emergent nanocatalysts. Organic ligands are conventionally used to stabilize metal nanoclusters by preventing uncontrolled aggregation and disintegration. However, excessive ligand shielding will hinder the accessibility to catalytically active sites, thereby often hampering nanoclusters’ catalytic activity. Thus, constructing metal nanoclusters that are both stable and catalytically active is challenging but crucial for the discovery of efficient nanocluster catalysts. In addition to acting as conventional spectator ligands to stabilize nanoclusters and regulate their electronic structures, functional ligands may directly interact with reactants or reagents to promote the reaction or, in situ, release vacant metal sites that participate in catalysis via hemilabile coordination. This minireview outlines recent advances in metal nanocluster catalysis from a ligand perspective, focusing on the role of functional ligands in catalysis. We first provide a general overview of metal nanoclusters. Then, we delve into functional ligand‐participated metal nanocluster catalysis from the following aspects: i) Functional ligands furnishing organocatalytic sites, including Lewis basic sites or hydrogen bond donors/acceptors, in catalysis. ii) Anchoring catalytically active metal complex units onto nanoclusters using functional ligands. iii) Hemilabile ligands liberating vacant metal sites for catalysis. Finally, an outlook is provided.