Showing papers on "Borospherene published in 2012"

Polymorphism of two-dimensional boron.

Abstract: The structural stability and diversity of elemental boron layers are evaluated by treating them as pseudoalloy B1–x⬡x, where ⬡ is a vacancy in the close-packed triangular B lattice. This approach allows for an elegant use of the cluster expansion method in combination with first-principles density-functional theory calculations, leading to a thorough exploration of the configurational space. A finite range of compositions x is found where the ground-state energy is essentially independent of x, uncovering a variety of stable B-layer phases (all metallic) and suggesting polymorphism, in stark contrast to graphene or hexagonal BN.

B22- and B23-: all-boron analogues of anthracene and phenanthrene.

Abstract: Clusters of boron atoms exhibit intriguing size-dependent structures and chemical bonding that are different from bulk boron and may lead to new boron-based nanostructures. We report a combined photoelectron spectroscopic and ab initio study of the 22- and 23-atom boron clusters. The joint experimental and theoretical investigation shows that B22– and B23– possess quasi-planar and planar structures, respectively. The quasi-planar B22– consists of fourteen peripheral atoms and eight interior atoms in a slightly buckled triangular lattice. Chemical bonding analyses of the closed-shell B222– species reveal seven delocalized π orbitals, which are similar to those in anthracene. B23– is a perfectly planar and heart-shaped cluster with a pentagonal cavity and a π-bonding pattern similar to that in phenanthrene. Thus, B22– and B23–, the largest negatively charged boron clusters that have been characterized experimentally to date, can be viewed as all-boron analogues of anthracene and phenanthrene, respectively. ...

A photoelectron spectroscopy and ab initio study of B21-: negatively charged boron clusters continue to be planar at 21.

Abstract: The structures and chemical bonding of the B21− cluster have been investigated by a combined photoelectron spectroscopy and ab initio study The photoelectron spectrum at 193 nm revealed a very high adiabatic electron binding energy of 438 eV for B21− and a congested spectral pattern Extensive global minimum searches were conducted using two different methods, followed by high-level calculations of the low-lying isomers The global minimum of B21− was found to be a quasiplanar structure with the next low-lying planar isomer only 19 kcal/mol higher in energy at the CCSD(T)/6-311-G* level of theory The calculated vertical detachment energies for the two isomers were found to be in good agreement with the experimental spectrum, suggesting that they were both present experimentally and contributed to the observed spectrum Chemical bonding analyses showed that both isomers consist of a 14-atom periphery, which is bonded by classical two-center two-electron bonds, and seven interior atoms in the planar str