Planar or quasi-planar octa- and ennea-coordinate aluminum and gallium in boron rings

Abstract

An ab initio theoretical investigation has been performed on planar or quasi-planar octa-and ennea-coordinate Al and Ga centered in X@B 8 − and X@B 9 (X=Al, Ga). These high symmetry molecular wheels all turned out to be true minima of the systems and σ+π double aromatic in nature, similar to the previously characterized D 8h B@B 8 − both electronically and geometrically. Adiabatic and vertical detachment energies of the anions and the ionization potentials of the neutrals have been calculated to aid their eventual experimental identification.planar hyper-coordinate, aluminum, gallium, ab initio, geometry, electronic structure

Observation of the Highest Coordination Number in Planar Species: Decacoordinated Ta©B10− and Nb©B10− Anions

“…[10,11] A series of planar wheel-type boron rings with a main group atom in the center and coordination numbers 6-10 have been probed theoretically. [12][13][14] So far the joint PES and ab initio studies of aluminum-doped boron clusters showed that the aluminum atom avoids the central position in the AlB 6 À , AlB 7 À , AlB 8 À , AlB 9 À , AlB 10 À , and AlB 11 À systems.[ [15][16][17] Recently, a transition-metal-doped boron cluster, RuB 9 À , with the highest coordination number known to date was reported.[18] We developed a chemical bonding model, which allows the design of planar molecules with high coordination numbers.[18] According to the model, 2n electrons in the MB n species form n 2c-2e peripheral B-B s bonds. The remaining valence electrons form two types of delocalized bonding, in-plane s and out-of-plane p bonding, and therefore, should satisfy the (4N + 2) Hückel rule separately for s and p aromaticity to attain highly symmetric structures with high electronic stability.…”

B19−: ein aromatischer Wankel‐Motor

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Huang et al entdeckten vor kurzem die energetisch stabilste Struktur von B 19À (1): eine Radstruktur, bestehend aus zwei ineinandergeschachtelten ebenen aromatischen p-Systemen.[ In den letzten zehn Jahren wurden mithilfe der Computerchemie mehrere radförmige Borstrukturen vorgeschlagen, die Hauptgruppenelement- [8][9][10][11][12][13][14] oder Übergangsmetallato-me [15][16][17][18]

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M@B9 and M@B10 molecular wheels containing planar nona- and deca-coordinate heavy group 11, 12, and 13 metals (M=Ag, Au, Cd, Hg, In, Tl)

“…Our group also proposed a universal structural pattern for planar hyper-coordinate Si in B n H 2 Si which contained fan-shaped B n frames as ligands [10] , and predicted the possibility of planar octa-and nona-coordinate group 13 elements centered in D nh M@B 8 − and M@B 9 wheels (M=Al, Ga) at DFT and ab initio levels [11] . However, to the best of our knowledge, there have been no investigations on planar nona-or decacoordinate heavy group 11, 12 and 13 metals reported to date.…”