Realizing high stability with superior catalytic activity in nanoclusters via an in situ ligand stripping strategy

The significance of cluster-based catalysts lies in their exceptional catalytic activity and high selectivity, enabled by atomically precise design. However, in many cases, the catalytic activity and stability of cluster catalysts are mutually exclusive, and this severely hinders their widespread application. In contrast to previous strategies, which are mostly based on balancing stability and activity, this study develops an in situ phosphine ligand stripping strategy, which endows clusters with the long-time pursued, concurrent high stability and catalytic activity. Of note, after the phosphine ligand is cleaved by the R group, it forms a covalent bond with the metal atom in the cluster instead of the traditional coordinate bond, which enhances the cluster stability. Meanwhile, the lone pair electrons retained by phosphorus as the anchoring atom further modulate the metal's electronic structure and enrich the substrate. Consequently, the bridging phosphido (µ-PR₂)-ligand-bearing Au₁₈Cd₄(SR)₁₂(DPP)₆ cluster exhibits a 2- to 10-fold increase in catalytic yield compared to related clusters. A series of comparative experiments, characterization studies, and DFT theoretical calculations reveal a new reaction mechanism, confirming that surface cadmium atoms serve as catalytically active sites; at the same time, µ-PR₂ facilitates substrate enrichment around the catalyst.