Hydrogenation of B: A Planar-to-Icosahedral Structural Transition in BH ( n = 1-6) Boron Hydride Clusters.

A systematic density functional theory and wave function theory investigation performed in this work reveals a planar-to-icosahedral structural transition between n = 4-5 in the partially hydrogenated BH clusters ( n = 1-6) upon hydrogenation of all-boron B. Coupled cluster calculations with triple excitations (CCSD(T)) indicate that a distorted icosahedral BH cluster with C symmetry is overwhelmingly favored (by 35 kcal/mol) over the recently proposed perfectly planar borozene (D BH) (Szwacki et al., Nanoscale Res Lett 4:1085, 2009) which proves to be a high-lying local minimum. A similar 2D-3D structural transition occurs to the corresponding boron boronyl analogues of B(BO) with n -BO terminals. Detailed adaptive natural density partitioning (AdNDP) analyses reveal the bonding patterns of these quasi-planar or cage-like clusters which are characterized with delocalized σ and π molecular orbitals. The electron detachment energies of the concerned anions and excitation energies of the neutrals are also predicted to facilitate their future experimental characterizations. [ABSTRACT FROM AUTHOR]