Aromatic Boron Wheels with More than One Carbon Atom in the Center: C₂B₈, C₃B₉³⁺, and C₅B₁₁⁺

Computational exploration of carboranes of formula CnBmq+ reveals that more than one hypercoordinated carbon atom can be enclosed by a peripheral ring comprising a suitable number of boron atoms. The C2B8, C3B93+, and C5B11+ species (the LUMO of the latter is shown) are stabilized by substantial Hückel π aromaticity. Furthermore, multicenter σ bonding helps bind the inner carbon units to the boron perimeters, though they can freely rotate relative to one another. Supporting information for this article is available on the WWW under http://www.wiley-vch.de/contents/jc_2002/2005/z461970_s.pdf or from the author. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.