Structures and electronic properties of B2Si6−/0/+: anion photoelectron spectroscopy and theoretical calculations

Abstract

We measured the photoelectron spectrum of B₂Si₆⁻ anion and investigated the structures and electronic properties of B₂Si₆⁻ anion as well as those of its neutral and cationic counterparts with quantum chemical calculations. The vertical detachment energy (VDE) of the B₂Si₆⁻ anion has been measured to be 2.40 ± 0.08 eV. Through global minimum searches and CCSD(T) calculations, we have identified that the lowest-energy structures of B₂Si₆^q (q = −1, 0, +1) are peculiar structures with a Si atom hanging over a distorted bowl-like B₂Si₅ framework. Quasi-planar or planar isomers have also been identified for the B₂Si₆ cluster at −1, 0, and +1 charge states. The quasi-planar and planar isomers are higher in energy than their bowl-like counterparts by at least 0.20 eV. The symmetries of the quasi-planar isomers varied at different charge states, ranging from C_s to C_2h, then to D_2h respectively for the −1, 0, and +1 charge states. The reducing of the symmetry from +1 charge state to −1 charge state is more likely due to the Jahn–Teller effect upon the addition of electrons.