1,2,3-Triazolium-1-oxide, -1-imide and 1-methanide hetero-1,3,5-triene equilibrium: ab initio calculations. A new base induced ring expansion of 1-alkyl-1,2,3-triazolium salts to 2,3-dihydro-1,2,4-triazines and 1-amino-imidazoles via the 1,2,5-triazahexa-1,3,5-triene system. Azolium 1,3-dipoles