http://www.arkat-usa.org/get-file/37295/

Pyridinium-N-(2-pyridyl)aminides and related compounds: a theoretical study. 

Seven families of pyridinium-N-(heteroaryl)aminides, both azinyl and azolyl, have been studied. For each family, three structures have been considered, the "classical" and two radicals. The transition states corresponding to the rotation  of the pyridinium and  the heterocycle were calculated at the B3LYP/6-31G* level.