Dynamical fluxionality, multiplicity of structural forms, and electronic properties of the B3Si11 cluster: anion photoelectron spectroscopy and theoretical calculations

Abstract

The geometrical structures and electronic properties of anionic, neutral, and cationic B₃Si₁₁ clusters were investigated by performing ab initio calculations combined with size-selected anion photoelectron spectroscopy. The experimental photoelectron spectrum of the B₃Si₁₁⁻ anion is reasonably reproduced by theoretical simulations of two competing isomers. The global minimum of the B₃Si₁₁⁻ anion is formed by the fusion of a B₃Si₇ bicapped tetragonal antiprism to a B₃Si₄ pentagonal bipyramid by sharing a B₃ triangle, while that of neutral B₃Si₁₁ has a B₃-endohedral sandwich structure composed of a Si₅ five-membered ring and a Si₆ six-membered ring, and that of the 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, neutral B₃Si₁₁ exhibits σ + π double delocalized bonding patterns. Anionic, neutral, and cationic B₃Si₁₁ clusters 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 showed that the three B atoms in B₃Si₁₁ have strong bonding interactions.