(E)-5-[(3-Ethoxy-2-hydroxybenzylidene)amino]-1,3,4-thiadiazole-2(3H)-thione

In the title compound, C11H11N3O2S2, the dihedral angle between the benzene ring and the five-membered ring is 6.85 (9)°. An intramolecular O—H⋯N hydrogen bond makes an S(6) ring motif. In the crystal, molecules are linked through bifurcated N—H⋯(O,O) hydrogen bonds with R 1 2(5) ring motifs, forming chains along the b axis. A short C⋯S contact [3.3189 (19) Å], which is shorter than the sum of the van der Waals radii of these atoms (3.50 Å), occurs in the structure. The crystal structure is further stabilized by C—H⋯N hydrogen bonding and π–π interactions [centroid–centroid distance = 3.7649 (12) Å].

In the title compound, C 11 H 11 N 3 O 2 S 2 , the dihedral angle between the benzene ring and the five-membered ring is 6.85 (9) . An intramolecular O-HÁ Á ÁN hydrogen bond makes an S(6) ring motif. In the crystal, molecules are linked through bifurcated N-HÁ Á Á(O,O) hydrogen bonds with R 1 2 (5) ring motifs, forming chains along the b axis. A short CÁ Á ÁS contact [3.3189 (19) Å ], which is shorter than the sum of the van der Waals radii of these atoms (3.50 Å ), occurs in the structure. The crystal structure is further stabilized by C-HÁ Á ÁN hydrogen bonding andinteractions [centroid-centroid distance = 3.7649 (12) Å ].
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: FF2044).

Comment
The biological versatility of compounds incorporating a thiadiazole ring is well known (Kumar et al., 1988;Yadav et al., 1989).
The asymmetric unit of the title compound, Fig. 1, comprises a thione-Schiff base ligand. The bond lengths (Allen et al., 1987) and angles are within the normal ranges and are comparable to the related structures (Zhang, 2003;Kargar et al., 2011).

Experimental
The title compound was synthesized by adding 3-ethoxy-salicylaldehyde (1 mmol) to a solution of 5-aminothiophene-2-thiol (1 mmol) in ethanol (30 ml). The mixture was refluxed with stirring for half an hour. The resultant solution was filtered.
Yellow single crystals of the title compound suitable for X-ray structure determination were recrystallized from ethanol by slow evaporation of the solvents at room temperature over several days.