4-[(2-Bromobenzylidene)amino]-3-(pyridin-4-yl)-1H-1,2,4-triazole-5(4H)-thione

In the title compound, C14H10BrN5S, the dihedral angle between the triazole ring and the pyridine and bromobenzene rings are 26.42 (13) and 6.28 (13)°, respectively. The molecule exists as a thione in the solid state. In the crystal, molecules are linked by N—H⋯N hydrogen bonds, generating [010] C(8) chains.

In the title compound, C 14 H 10 BrN 5 S, the dihedral angle between the triazole ring and the pyridine and bromobenzene rings are 26.42 (13) and 6.28 (13) , respectively. The molecule exists as a thione in the solid state. In the crystal, molecules are linked by N-HÁ Á ÁN hydrogen bonds, generating [010] C(8) chains.   Table 1 Hydrogen-bond geometry (Å , ).
We gratefully acknowledge financial support by the Doctoral Research Fund of Henan University of Traditional Chinese Medicine. Single-crystal X-ray diffraction analysis reveals that the title compound crystallizes in the monoclinic space group C2/c.
As shown in Fig. 1, the dihedral angle between the pyridyl and triazole rings is 153.6 °. As shown in Fig. 2, the crystal structure is stabilized by intermolecular hydrogen bonds N-H···N.

Experimental
In round bottom flask, 4-pyridine carboxylic acid (0.01 mol) and hydrazine hydrate 99% (0.01 mol) were taken along with alcohol and the mixture was refluxed for 4 h. Then from the reaction mixture alcohol was removed under reduced pressure. Solid residue was obtained, recrystallized from ethanol. In a 250 ml round bottom flask, 4-pyridine hydrazide (0.075 mol) was taken. To this a solution of potassium hydroxide (0.075 mol) in 100 ml of absolute alcohol and carbon disulfide were added agitated for overnight. The reaction mixture was diluted with 200 ml of dry ether. The solid obtained was 15.05 g (80%). It was filtered and washed with dry ether. A mixture of potassium-pyridine-dithiocarbazate (0.1 mol) and hydrazine hydrate 5 ml (0.1 mol) was refluxed for 2 h with occasional shaking and the solution was poured into the cold water. The mixture was acidified with hydrochloric acid. The precipitate obtained was filtered, dried and recrystallized by using alcohol. A mixture of 5-pyridine-4-amino-3-mercapto-4(H)-1,2,4-triazole (0.01 mol) taken with 2bromobenzaldehyde (0.01 mol) and concentrated sulfuric acid (0.5 ml) in ethanol 100 ml. The mixture was refluxed on water bath for several hours with TLC monitoring. The solid was obtained on cooling the mixture and poured in cold water was afforded the the title compound. Colourless prisms were grown from ethanol solution.

Refinement
All the H atoms were positioned geometrically (C-H = 0.93-0.97 Å) and refined as riding with U iso (H) = 1.2U eq (C) or 1.5U eq (methyl C).  The molecular structure of (I). Displacement ellipsoids are drawn at the 30% probability level and H atoms are shown as small spheres of arbitrary radii.  The crystal packing for (I). Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > σ(F 2 ) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )
x y z U iso */U eq