B3@Si12+: strong stabilizing effects of a triatomic cyclic boron unit on tubular silicon clusters

Abstract

Remarkably strong effects of the aromatic B₃ cycle in stabilizing tubular silicon clusters were observed for the first time. The doped cluster B₃@Si₁₂⁺ presents a novel structural motif for silicon clusters in which a B₃ cycle is encapsulated into a (6 × 2) Si₁₂ prism giving rise to a high symmetry stable tubular structure (D_3h). A large amount of electron density is transferred to the boron cycle, and the B₃^δ− unit not only retains a delocalized bonding pattern within the Si₁₂ prism but also enables a two-fold aromaticity for the resulting silicon double ring. This double ring can be used as a building block to make longer nanotubes.