What Determines If a Ligand Undergoes Coordination or Catalytic Activation on a Metal Cluster?

We report a joint experimental and theoretical study on the reactivity of Ag⁺ clusters with H₂S, D₂O, and NH₃. Complete dehydrogenation products are observed for Ag⁺ reacting with H₂S, but no dehydrogenation products are found for D₂O or NH₃ under the same reaction condition. Theoretical calculations elucidate why Ag⁺ clusters show different reactivities with these inorganic hydrides. NH₃ shows strong coordination with Ag⁺, but the dehydrogenation reactions are unfavorable; in contrast, the fragile H-S bonds and stable AgS⁺ products facilitate the hydrogen evolution of H₂S on Ag⁺. We fully analyzed the metal-ligand interactions of Ag⁺ clusters with three molecules and illustrated the reaction dynamics and charge-transfer interactions and altered the superatomic states during the formation of cluster sulfides. We expect this study to benefit the design of stable environmentally friendly desulfurization catalysts and also the understanding of the mechanism on ligand-protected metal clusters in wet chemistry.