Synthesis, molecular and crystal structure of 1-(1,2-dihydrophthalazin-1-ylidene)-2-[1-(thiophen-2-yl)ethylidene]hydrazine

Abstract

The title compound, C14H12N4S, was synthesized by the condensation reaction of hydralazine and 2-acetylthiophene and during the reaction, a proton transfer from the imino nitrogen atom to one of the endocylic nitrogen atoms occurred. The compound crystallizes in the monoclinic crystal system with two independent molecules (molecules 1 and 2) in the asymmetric unit. In each molecule, there is a slight difference in the orientation of the thiophene ring with respect to phthalazine ring system, molecule 1 showing a dihedral angle of 42.51 (1)° compared to 8.48 (1)° in molecule 2. This implies an r.m.s deviation of 0.428 (1) Å between the two molecules for the 19 non-H atoms. The two independent molecules are connected via two N—H...N hydrogen bonds, forming dimers which interact by two bifurcated π–π stacking interactions to build tetrameric motifs. The latter are packed in the ac plane via weak C—H...π interactions and along the b axis via C—H ...N and C—H...π interactions. This results a three-dimensional architecture with a tilted herringbone packing mode.

Keywords

• 2-Acetylthiophene-1-phthalazinylhydrazone
• bifurcated stacking interactions
• tetramers
• condensation reaction
• co-planar rings
• chevron-shaped motifs
• C—H...π interactions
• crystal structure