Mechanistic Study of the Hydride Migration-Induced Reversible Isomerization in Au₂₂(SR)₁₅H Isomers

Unraveling the evolution mechanism of metal nanoclustersis ofgreat importance in understanding the formation and evolution of metalliccondensed matters. In this work, the specific evolution process betweena pair of gold nanocluster (Au NC) isomers is completely revealedby introducing hydride ligands to simplify the research system. Ahydride-containing Au NC, Au-22(SR)(15)H, was synthesizedby kinetic control, and the positions of the hydrides were then confirmedby combining X-ray diffraction, neutron diffraction, and DFT calculations.Importantly, a reversible structural isomerization was found to occuron this Au-22(SR)(15)H. By combining the crystalstructures and theoretical calculations, the focus was placed on thehydride-binding site, and a [Au-H] migration mechanism of thisisomerization process is clearly shown. Furthermore, this [Au-H]migration mechanism is confirmed by the subsequent capture and structuraldetermination of theoretically predicted intermediates. This workprovides insight into the dynamic behavior of hydride ligands in nanoclustersand a strategy to study the evolution mechanism of nanoclusters bytaking the hydride ligand as the breakthrough point.