Syntheses and Antioxidant Activity of 1-Isonicotinoyl-4-phenylthiosemicarbazide and Crystal Structures of N-Phenyl-5-(pyridin-4-yl)-1,3,4-oxadiazol-2-amine Hydrochloride and 4-Phenyl-3-(pyridin-4-yl)-1H-1,2,4-triazole-5(4H)-thione derived from 1 Isonicotinoyl-4-phenylthiosemicarbazide

The title compound C13H12N4OS (I) is synthetized from isonicotinic hydrazide and isothiocynate. Compounds C13H11N4OCl (II) and C13H10N4S (III) where obtained upon reaction of (I) with Fe(II) or Mn(II) salts. Compound (II) is heterocyclic 1,3,4-oxadiazole while compound (III) is heterocyclic 1,2,4-triazole. The 1,3,4-oxadiazol derivative is almost planar with dihedral angle of 2.66 (8) and 5.14 (8)° between 1,3,4-oxadiazole ring and phenyl and pyridinium rings respectively; the dihedral angle between the phenyl and pyridinium rings is 3.92 (8)°. The 1,2,4-triazole derivative is non-planar. The phenyl and pyridyl rings form dihedral angles of 58.35 (5) and 58.33 (5)°, respectively, with the 1,2,4-triazole ring; the dihedral angle between the phenyl and pyridyl rings is 36.85 (4)°. In the compound (II) intramolecular hydrogen bonds of type N—H···Cl, C—H···N and C—H···Cl resulting in S(6) ring stabilize the structure. Intermolecular hydrogen bonds of type N—H···N, C—H···N, C—4···Cl link the molecule thus forming a three-dimensional network. In the structure of compound (III), intermolecular hydrogen bonds of type N—H···N, C—H···N, C—H···S1,link the monomer in a three-dimensional network.