The boron conundrum: Bonding in the bowl B30 and B36, fullerene B40 and triple ring B42 clusters

Geometries and bonding of B-30, B-36, B-40 and B-42 clusters were studied using quantum chemical computations. The bowl B-30 and B36 and planar B42 clusters exhibit disk aromaticity. Diatropic ring current is strong in B-30 and weaker in B-42. A fullerene-like B-40 (D-2d) having two hexagons and four heptagons was found as the lowest-lying isomer. Such a fullerene whose MOs closely mimic those of the buckyball B-80, represents novel structural feature of boron clusters. The most stable B-42 (C-2h) isomer is a triple ring tube with consistent sigma + pi diatropic magnetic responses making it a tubular aromatic species. (C) 2014 Elsevier B.V. All rights reserved.