Multisubstituted Imidazolo[4,5-d]pyridazine Fused Ring System Resulting from Nitroamine–Nitroimine Tautomerism

A series of multisubstituted imidazolo[4,5-d]pyridazine fused ring compounds was synthesized in which nitroamine-nitroimine tautomerism is exhibited. The electrostatic potential indicates that the nitroimino group has the lowest negative value, second only to the nitro group, culminating in the nitroamino area, which has the highest positive value. In addition, a strong hydrogen bond system which arises from the newly formed nitroimino tautomer suggests that the nitroimino is more stable than its nitroamino analogue.