Extremely stable metal-encapsulated AlPb10+ and AlPb12+ clusters:: Mass-spectrometric discovery and density functional theory study -: art. no. 163401

We report the experimental discovery of extremely stable metal-encapsulated superatom clusters of a group IVA element: AlPb10+ and AlPb12+. Ab initio density functional geometry optimizations at the B3LYP/LANL2DZ level result in a perfect icosahedron with an exceptionally large HOMO-LUMO gap of 3.1 eV for AlPb12+, and a related structure with D-4d symmetry for AlPb10+, with a HOMO-LUMO gap of 2.6 eV. Their high stability is attributed to the reinforcing influence of the most favorable closed-packed structure and optimally filled electron shells.