Structures, Stabilities, and Electronic Properties of Endo- and Exohedral Complexes of T10−Polyhedral Oligomeric Silsesquioxane Cages

Abstract

The geometries of endohedral and exohedral complexes of the polyhedral oligomeric silsesquioxane (POSS) cage molecule (HSiO3/2)10 with the atomic or ionic species Li0, Li+, Li-, Na0, Na+, Na-, K0, K+, K-, F-, Cl-, Br-, He, Ne, and Ar have been optimized at the B3LYP/6-311G(d,p) level of theory. Single point MP2 calculations were carried out at the DFT-optimized geometries. The properties of these complexes depend on the nature of the species encapsulated in, or attached to, the (HSiO3/2)10 cage. Encapsulation of noble gas atoms (He, Ne, and Ar) has almost no effect on the cage geometry. Encapsulation of alkali metal cations, in contrast, exhibits attractive interactions with cage oxygen atoms and leads to cage shrinkage. Encapsulation of halide ions results in cage expansion. Endohedral Li+, Li-, Na+, F-, Cl-, and Br- complexes are energetically favored relative to the separated species. The fluoride ion is predicted to migrate into the (HSiO3/2)10 cage with little or no energy barrier with the cage remai...