2019 年 13 巻 1 号 p. A0108-
Ligand-protected gold clusters with specific compositions exhibit high stability due to symmetrical geometric structures, closed electronic structures of the gold cores, and complete passivation of the surface gold atoms by the ligands. In this regard, they can be viewed as chemically-modified superatoms in which valence electrons are accommodated into atomic-like discrete orbitals. This review article highlights the geometric and electronic structures of superatoms with reference to those of conventional atoms and their bonding scheme to form quasi-molecules (superatomic molecules). Our recent efforts to characterize their structures in the gas phase are also described.