The title compound, C14H12N4S, was synthesized by the condensation reaction of hydralazine and 2-acetyl-thio-phene and during the reaction, a proton transfer from the imino nitro-gen atom to one of the endocylic nitro-gen atoms occurred. The compound crystallizes in the monoclinic crystal system with two independent mol-ecules (mol-ecules 1 and 2) in the asymmetric unit. In each mol-ecule, there is a slight difference in the orientation of the thio-phene ring with respect to phthalazine ring system, mol-ecule 1 showing a dihedral angle of 42.51 (1)° compared to 8.48 (1)° in mol-ecule 2. This implies an r.m.s deviation of 0.428 (1) Å between the two mol-ecules for the 19 non-H atoms. The two independent mol-ecules are connected via two N-H⋯N hydrogen bonds, forming dimers which inter-act by two bifurcated π-π stacking inter-actions to build tetra-meric motifs. The latter are packed in the ac plane via weak C-H⋯π inter-actions and along the b axis via C-H ⋯N and C-H⋯π inter-actions. This results a three-dimensional architecture with a tilted herringbone packing mode.
Keywords: 2-Acetylthiophene-1-phthalazinylhydrazone; C—H⋯π interactions; bifurcated stacking interactions; chevron-shaped motifs; co-planar rings; condensation reaction; crystal structure; tetramers.