C-Adducts of 5-(het)aryl-2,3-dicyano-1-pyrazinium salts containing a residue of a 1,3-dicarbonyl compound at position 6 can be involved in the cyclization with hydrazine hydrate giving rise to pyrazino[2,3-c]pyridazines along with the expected pyrazole derivatives. The reactions of the same ?H-adducts with hydroxylamine unexpectedly afforded triazacyclopenta[a]indene derivatives. The crystallographic data on the three-dimensional structures of new polycyclic compounds were obtained