B3@Si12+: strong stabilizing effects of a triatomic cyclic boron unit on tubular silicon clustersElectronic supplementary information (ESI) available. See DOI: 10.1039/c8cp00380g

Remarkably strong effects of the aromatic B 3 cycle in stabilizing tubular silicon clusters were observed for the first time. The doped cluster B 3 @Si 12 + presents a novel structural motif for silicon clusters in which a B 3 cycle is encapsulated into a (6 × 2) Si 12 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 B 3 δ − unit not only retains a delocalized bonding pattern within the Si 12 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. Remarkably strong effects of the aromatic B 3 cycle in stabilizing tubular silicon clusters were observed for the first time.