The geometric structures of X@Ag54 clusters were similar each other, with both containing an X@{Ag12S8} core (Figures 1A and 1B). In this core, the central anion X (S 2-or I -) was surrounded by 12 Ag atoms, forming an icosahedron (point group Ih) (Figure ), with 8 S atoms in a cubic arrangement surrounding this core. On the surface of the X@{Ag12S8} core, 12 S atoms formed an intermediate layer (highlighted in yellow, Figure ), which was connected to outer Ag42(S t Bu)20.