Mechanistic Study of the Hydride Migration-Induced Reversible Isomerization in Au 22 (SR) 15 H Isomers

Unraveling the evolution mechanism of metal nanoclusters is of great importance in understanding the formation and evolution of metallic condensed matters. In this work, the specific evolution process between a pair of gold nanocluster (Au NC) isomers is completely revealed by introducing hydride ligands to simplify the research system. A hydride-containing Au NC, Au 22 (SR) 15 H, was synthesized by kinetic control, and the positions of the hydrides were then confirmed by combining X-ray diffraction, neutron diffraction, and DFT calculations. Importantly, a reversible structural isomerization was found to occur on this Au 22 (SR) 15 H. By combining the crystal structures and theoretical calculations, the focus was placed on the hydride-binding site, and a [Au–H] migration mechanism of this isomerization process is clearly shown. Furthermore, this [Au–H] migration mechanism is confirmed by the subsequent capture and structural determination of theoretically predicted intermediates. This work provides insight into the dynamic behavior of hydride ligands in nanoclusters and a strategy to study the evolution mechanism of nanoclusters by taking the hydride ligand as the breakthrough point.