Two Schiff base derivatives of 4-amino-3-propyl-1,2,4-triazole-5-thione

The Schiff base compounds 4-isopropylideneamino-3-propyl-4,5-dihydro-1H-1,2,4-triazole-5-thione, C₈H₁₄-N₄S, (I), and 4-[1-(2-hydroxyphenyl)ethylideneamino]-3-propyl-4,5-dihydro-1H-1,2,4-triazole-5- thione, C₁₃H₁₆-N₄OS, (II), contain essentially planar triazole rings in which the corresponding bond distances and angles are equivalent within experimental error. Both compounds show the same anti conformation of the propyl groups, however, they differ in the positioning of the functional groups on N atom. The isopropylidene group in (I) and the 1-(2-hydroxyphenyl)ethylideneamino group in (II) are rotated approximately 77° in opposite directions about the N - N bond relative to the triazole ring. In the case of (II), the adopted conformation permits an intramolecular hydrogen bond between the hydroxyl-H atom and the amine-N atom. Both compounds form hydrogen-bonded dimers through N - H ⋯ S interactions involving the thione-S atom and the adjacent protonated N atom on the ring. The structural features of these compounds are compared with those of similar amine-and thione-substituted triazoles and their Schiff base derivatives.