Hydride, chloride, and bromide show similar electronic effects in the Au₉(PPh₃)₈³⁺ nanocluster

Recent experimental and computational results have suggested that a hydride bound to the Au₉(PPh₃)₈³⁺ gold nanocluster donates its electrons to the metal core, forming an 8-electron cluster. We present electronic absorption spectra of precisely mass-selected Au₉(PPh₃)₈³⁺ clusters featuring a surface hydride, chloride, or bromide. Comparison of these spectra shows that H^-, Cl^-, or Br^- perturb the electronic structure of the Au₉(PPh₃)₈³⁺ core in similar ways. This suggests that hydride and halides play similar roles electronically in this cluster, and thus are either both metallic or both ligand-like.