Tailoring Atomically Precise Gold Nanoclusters for Boosting Selective Hydrogenation of Nitrostyrene with H2

Hydrogenation reactions represent some of the most extensively studied topics within the field of catalysis. A novel alkynyl and phosphine coprotected [Au34(PhCC)14(Ph3P)6]­(SO3CF3)2(1) nanocluster has been synthesized, and its structure was determined by single crystal X-ray diffraction (SCXRD). Density functional theory calculation shows that 1 features an 18-electron superatomic molecule character with a configuration of (1σ)2(1n)2(1π)2(2σ)2(1σ*)2(3σ)2(2n)2(3n)2(1π*),2 which is significantly different from previously reported 18-electron metal nanoclusters. In comparison with some gold nanoclusters with similar composition or size but different ligands or surface coordination structures, except for the ligand effect (different kinds of ligands), the surface coordination structure involving the Au­(I) sites derived from the PhCC–Au–CCPh monomeric staple motif and the steric hindrance of PhCC and Ph3P on the surface of 1, and the special electronic structure play a critical role in ensuring the enhanced catalytic performance of 1/TiO2 toward the chemoselective hydrogenation of 4-nitrostyrene with H2. The turnover frequency (TOF) of 1322.5 h–1 and the turnover number (TON) of 23500 represent the highest values observed among the gold nanocluster-based catalysts toward the same reaction. It presents an example of tailoring the surface coordination structure to modulate the catalytic performance, and offers valuable insights for the rational design and synthesis of catalysts to trade off the catalytic activity and selectivity at the atomic level.