Dynamical fluxionality, multiplicity of structural forms, and electronic properties of the BSi cluster: anion photoelectron spectroscopy and theoretical calculations.

The geometrical structures and electronic properties of anionic, neutral, and cationic BSi clusters were investigated by performing ab initio calculations combined with size-selected anion photoelectron spectroscopy. The experimental photoelectron spectrum of the BSi anion is reasonably reproduced by theoretical simulations of two competing isomers. The global minimum of the BSi anion is formed by the fusion of a BSi bicapped tetragonal antiprism to a BSi pentagonal bipyramid by sharing a B triangle, while that of neutral BSi has a B-endohedral sandwich structure composed of a Si five-membered ring and a Si six-membered ring, and that of the BSi cation adopts a Si tricapped tetragonal antiprism with three face-capping B atoms.