title: Novel superalkali superhalogen compounds (Li3)+(SH)- (SH=LiF2, BeF3, and BF4) with aromaticity: new electrides and alkalides.
abstract: Optimized structures, with all real frequencies, of superalkali superhalides (Li(3))(+)(SH)(-) (SH=LiF(2), BeF(3), and BF(4)), are obtained, for the first time, at the B3LYP/aug-cc-pVDZ and MP2/aug-cc-pVDZ computational levels. These superalkali superhalides possess three characteristics that are significantly different from normal alkali halides. 1) They have a variety of structures, which come from five bonding mode types: edge-face, edge-edge, face-face, face-edge, and staggered face-edge. We find that the bonding mode type closely correlates with the Li(3)-SH bond energy. 2) The valence electrons on the Li(3) ring are pushed out by the (SH)(-) anion, and become excess electrons, conferring alkalide or electride characteristics on these Li(3)-SH species, depending on the bonding mode type. 3) The highest occupied molecular orbital of each Li(3)-SH species is a doubly occupied delocalized sigma bonding orbital on the Li(3) ring, which indicates its aromaticity. It is noticeable that the maximum negative nucleus-independent chemical shift value (about -10 ppm) moves out from the center of the Li(3) ring, owing to repulsion by the SH(-) anion. We find that these superalkali superhalides are not only complicated "supermolecules", but are also a new type of alkalide or electride, with aromaticity.
authors.affiliation: State Key Laboratory of Theoretical and Computational Chemistry, Institute of Theoretical Chemistry, Jilin University, Changchun 130023, P.R. China.
authors.forename: Fang-Fang
authors.initials: FF
authors.lastname: Wang
authors.forename: Zhi-Ru
authors.initials: ZR
authors.lastname: Li
authors.forename: Di
authors.initials: D
authors.lastname: Wu
authors.forename: Xiao-Ying
authors.initials: XY
authors.lastname: Sun
authors.forename: Wei
authors.initials: W
authors.lastname: Chen
authors.forename: Ying
authors.initials: Y
authors.lastname: Li
authors.forename: Chia-Chung
authors.initials: CC
authors.lastname: Sun