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

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 B2Si6q (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.