6-Chloro-3-(3-methyl­phen­yl)-1,2,4-triazolo[4,3-b]pyridazine

The title compound, C(12)H(9)ClN(4), was prepared from dichloro­pyridazine and tolyl­tetra­zole in a nucleophilic biaryl coupling followed by thermal ring transformation. The mol­ecule is essentially planar (r.m.s. deviation for all non-H atoms = 0.036 Å) and an intra­molecular C—H⋯N hydrogen bond occurs. In the crystal, the mol­ecules form dimers connected via π–π inter­actions [centroid–centroid distance = 3.699 (2) Å], which are further connected to neighbouring mol­ecules via C—H—N bonds. The bond lengths in the pyridazine ring system indicate a strong localization of the double bonds and there is a weak C—Cl bond [1.732 (3) Å].