Dynamical fluxionality, multiplicity of structural forms, and electronic properties of B3Si11 cluster: anion photoelectron spectroscopy and theoretical calculations
The geometrical structures and electronic properties of anionic, neutral, and cationic B3Si11 clusters were investigated by ab initio calculations combined with size-selected anion photoelectron spectroscopy. The experimental photoelectron spectrum of B3Si11ˉ anion is reasonably reproduced by theoretical simulations of two competing isomers. The global minimum of B3Si11ˉ anion is formed by fusion of a B3Si7 bicapped tetragonal antiprism to a B3Si4 pentagonal bipyramid by sharing a B3 triangle, while that of B3Si11 neutral has a B3-endohedral sandwich structure consisting of a Si5 five-membered ring and a Si6 six-membered ring, and that of B3Si11+ cation adopts a Si11 tricapped tetragonal antiprism with three face-capping B atoms. It is interesting that a Si5 five-membered ring and a Si6 six-membered ring are stabilized by three B atoms in B3Si11. The three B atoms tend to bond with each other to form a B3 triangle with stronger B–B bonds than B–Si bonds. Moreover, B3Si11 neutral exhibits σ + π double delocalized bonding patterns. Anionic, neutral, and cationic B3Si11 have multiplicity of structural forms and their low-lying isomers show dynamical fluxionality. The bond lengths, bond orders, MO, constant electronic charge density surfaces, and PDOS analyses found that the three B atoms in B3Si11 have strong bonding interactions.