Chemistry of the three-dimensionally aromatic CB11 cage
After a brief introduction to the electronic structure of the three-dimensionally aromatic icosahedral closo-monocarbadodecaborate anion CB11H12-, some recent results for its permethylated version, CB11Me12- and three highly reactive electroneutral analogs are presented and discussed. These are the radical CB11Me12·, the boronium ylide CB11Me11 with a naked boron vertex, and the isomeric carbonium ylide with a naked carbon vertex. These ylides are probably better viewed as unusual types of singlet borylene and carbene, respectively.