CRYSTAL STRUCTURES OF AZOLOPYRIDAZINES. Anna Katrusiak, S. Baloniak and A. Katrusiak⁺, Department of Organic Chemistry, Karol Marcinkowski University of Medical Sciences, Grunwaldzka 6, 60-780 Poznan, Poland. ⁺Department of Crystal Chemistry, Adam Mickiewicz University, Grunwaldzka 6, 60-780 Poznan, Poland

Crystal structures of several azolopyridazine derivatives will be presented, and the molecular aggregations and interactions compared and discussed. Triazolo- and tetrazolopyridazines show interesting biological and pharmacological activities and have been applied in various drugs [A. Deeb and S. A. Said, Collect. Czech. Chem. Commun. 55 (1990) 2795]. The pyridazine ring is a fragment of many compounds of a broad biological activity, for example bacteriostatic or cystostatic, and inhibitors in enzymatic processes [G. Biagi et al., Farmaco 47 (1992) 91]. The investigated series include 6-hydrazino-, 6-morpholino-, and 6-azido-1,2,3,4-tetrazolo[5,4-b]pyridazines, and 6-azido-1,2,3-triazolo[4,3-b]pyridazine. In the crystal lattices the molecules are usually arranged into planar sheets. Short intermolecular contacts CH...N have a character of weak hydrogen bonds, influence the molecular aggregation, and appear to be characteristic interactions in the structures of these compounds.