Synthesis and single-crystal X-ray diffraction analysis of new heterocyclic coloured materials. 3-Arylazo-8H-imidazo[1,2-b] pyrazolo[4,3-d]pyridazines

A simple synthetic strategy is described for the hitherto unreported 3-arylazo-8H-imidazo1,2-b]pyrazolo4,3-d]pyridazines 7 is described based on the reaction of 3-acetyl-4-cyano-1,5-diphenylpyrazole hydrazone 3 with the hydrazonoyl halides 1a-l. The structures of such dyes were confirmed by spectroscopic and X-ray crystallographic analyses. The mechanism of formation of such compounds was also discussed.