N-butylpyridinium undecachlorocarbadodecaborate and comparison with similar compounds.

The title compound, C(9)H(14)N(+)·CHB(11)Cl(11)(-), was obtained in the course of our continuing studies of the low-melting salts of closo- and nido-carborane cage anions with alkylpyridinium and dialkylimidazolium cations. The title compound is the first example of a pyridinium salt of a perchlorinated carborane anion. The structure consists of one N-butylpyridinium cation counterbalanced by one perchlorinated carborane cage anion per asymmetric unit. By changing the counter-ion, different packings are observed, and to try to understand this the new structure is compared with five similar compounds.