4-{3-[Hydroxy(phenyl)methyl]-5-thioxo-4,5-dihydro-1H-1,2,4-triazol-4-yl}benzenesulfonamide

In the title compound, C15H14N4O3S2, the hydroxy group is disordered over two positions with occupancies of 0.619 (5) and 0.381 (5). The benzene ring attached to the heterocycle makes a dihedral angle of 86.92 (9)° with respect to the best plane through the five-membered ring. The crystal packing is stabilized by intermolecular O—H⋯O, N—H⋯S, N—H⋯N, C—H⋯O and C—H⋯N hydrogen bonds, and N—H⋯π and C—H⋯π interactions.

In the title compound, C 15 H 14 N 4 O 3 S 2 , the hydroxy group is disordered over two positions with occupancies of 0.619 (5) and 0.381 (5). The benzene ring attached to the heterocycle makes a dihedral angle of 86.92 (9) with respect to the best plane through the five-membered ring. The crystal packing is stabilized by intermolecular O-HÁ Á ÁO, N-HÁ Á ÁS, N-HÁ Á ÁN, C-HÁ Á ÁO and C-HÁ Á ÁN hydrogen bonds, and N-HÁ Á Á and C-HÁ Á Á interactions.
Previous reports have also dealt with the annular tautomerism encountered in 1,2,4-triazoles in the solid state and in solution (Buzykin et al., 2008;Dolzhenko et al., 2010). For 3(5)-thioxo-1,2,4-triazoles, two tautomeric forms may exist in the solid state: the thione (C=S) and the thiol (SH), where the former has been supported by a recent X-ray diffraction study (Karayel et al., 2007). In this context, we prepared the title compound to determine its pharmacological potential and the preferred tautomeric form in the solid state.
The title molecule (Fig. 1) the aromatic rings (C1-C6 and C10-C15) are oriented at angles of 73.79 (10) and 86.92 (9)°w ith respect to the best plane through the five-membered ring. The dihedral angle between the two six-membered rings is 47.58 (9)°.
The precipitate thus obtained was filtered, washed with water and recrystallized from aqueous ethanol.

Refinement
The H atoms of the aromatic and hydroxyl groups were positioned geometrically with O-H = 0.82 Å, C-H = 0.93Å and refined using a riding model with U iso (H) = 1.2 or 1.5U eq (C,O). The H atoms of the NH 2 group were located in a difference Fourier synthesis and their positional parameters were refined with U iso (H) set to 1.2U eq (N). The N-H distances were restrained to 0.84 (1) Å. The H and O atoms of the hydroxyl group and the H atom of the C atom to which the hydroxyl group is attached are disordered in two alternative positions with occupancy factors 0.620 (4):0.380 (4). The C-O distances of the disordered hydroxyl group were restrained to 1.30 (1)Å. Fig. 1. View of the title compound with the atom numbering scheme. Displacement ellipsoids for non-H atoms are drawn at the 50% probability level. The minor occupied sites of the disordered atoms have been omitted for clarity.

Special details
Geometry. Bond distances, angles etc. have been calculated using the rounded fractional coordinates. All su's are estimated from the variances of the (full) variance-covariance matrix. The cell esds are taken into account in the estimation of distances, angles and tor-

sion angles
Refinement. Refinement on F 2 for ALL reflections except those flagged by the user for potential systematic errors. Weighted Rfactors wR and all goodnesses 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 observed criterion of F 2 > σ(F 2 ) is used only for calculating -R-factor-obs 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.