title: Chemical bonding in Si5(2-) and NaSi5(-) via photoelectron spectroscopy and ab initio calculations.
abstract: Photoelectron spectroscopy and ab initio calculations are used to investigate the electronic structure and chemical bonding of Si5(-) and Si5(2-) in NaSi5(-). Photoelectron spectra of Si5(-) and NaSi5(-) are obtained at several photon energies and are compared with theoretical calculations at four different levels of theory, TD-B3LYP, R(U)OVGF, UCCSD(T), and EOM-CCSD(T), all with 6-311+G(2df) basis sets. Excellent agreement is observed between experiment and theory, confirming the obtained ground-state structures for Si5(-) and Si5(2-), which are both found to be trigonal bipyramid with D3h symmetry at several levels of theory. Chemical bonding in Si5, Si5(-), and Si5(2-) is analyzed using NPA, molecular orbitals, ELF, and NICS indices. The bonding in Si5(2-) is compared with that in the isoelectronic and isostructural B5H5(2-) species, but they are found to differ due to the involvement of electron densities, which are supposed to be lone pairs in the skeletal bonding in Si5(2-).
authors.affiliation: Department of Chemistry and Biochemistry, Utah State University, Logan, Utah 84322-0300, USA.
authors.forename: Dmitry Yu
authors.initials: DY
authors.lastname: Zubarev
authors.forename: Alexander I
authors.initials: AI
authors.lastname: Boldyrev
authors.forename: Xi
authors.initials: X
authors.lastname: Li
authors.forename: Li-Feng
authors.initials: LF
authors.lastname: Cui
authors.forename: Lai-Sheng
authors.initials: LS
authors.lastname: Wang