An Octapositive Cation Incorporating Multiple Redox Centres: Cage Amine Complexes of Cobalt(III) Linked by a 2,2'-Bis(pyridinium) Unit

The methyl substituents of diquaternized 4,4'-dimethyl-2,2'-bipyridine are sufficiently acidic to be used as the source of a bridgehead carbon in the formation of cage amine derivatives from [Co(sen)](3+) [sen = 4,4',4"-ethylidynetris(3-azabutan-1-amine)]. The resulting octapositive bis(cage)-bipyridinium species can be obtained in both meso and optically active forms, the latter showing readily detectable potential shifts in the presence of enantiomeric anions.