Boron di- and tri-cations

Previous work on boron di- and tri-cations is reviewed. The structural chemistry of representative examples of these classes of compound has been probed by determination of the single-crystal X-ray structures of [(4-Mepy) 4 B]Br 3 and [py 3 BH]Br 2 . The electronic structures of the polycations [(py) 3 BH] 2+ , [(py) 3 BBr] 2+ , [(4-Mepy) 3 BH] 2+ , [(4-Mepy) 4 B] 3+ , [(Me 3 P) 3 BH] 2+ and [(Me 3 P) 4 B] 3+ have been examined by DFT methods. The atomic charges on these cations were evaluated by Mulliken, natural population analysis (NPA), Hirschfeld and Voronoi deformation density (VDD) methods. © 2008 The Royal Society of Chemistry.