Elucidating the Doping Effect on the Electronic Structure of Thiolate‐Protected Silver Superatoms by Photoelectron Spectroscopy

Gas‐phase photoelectron spectroscopy (PES) was conducted on [XAg 24 (SPhMe 2 ) 18 ] − (X=Ag, Au) and [YAg 24 (SPhMe 2 ) 18 ] 2− (Y=Pd, Pt), which have a formal superatomic core (X@Ag 12 ) 5+ or (Y@Ag 12 ) 4+ with icosahedral symmetry. PES results show that superatomic orbitals in the (Au@Ag 12 ) 5+ core remain unshifted with respect to those in the (Ag@Ag 12 ) 5+ core, whereas the orbitals in the (Y@Ag 12 ) 4+ (Y = Pd, Pt) core shift up in energy by about 1.4 eV. The remarkable doping effect of a single Y atom (Y=Pd, Pt) on the electronic structure of the chemically modified (Ag@Ag 12 ) 5+ superatom was reproduced by theoretical calculations on simplified model systems and was ascribed to 1) the weaker binding of valence electrons in Y@(Ag + ) 12 compared to Ag + @(Ag + ) 12 due to the reduction in formal charge of the core potential, and 2) the upward shift of the apparent vacuum level due to the presence of a repulsive Coulomb barrier between [YAg 24 (SPhMe 2 ) 18 ] − and electron.