3-(1-Benzofuran-2-yl)-1H-1,2,4-triazole-5(4H)-thione monohydrate

In the title hydrate, C10H7N3OS·H2O, the essentially planar benzofuran [maximum deviation = 0.006 (1) Å] and 4,5-dihydro-1H-1,2,4-triazole [maximum deviation = 0.007 (1) Å] rings form a dihedral angle of 11.67 (6)°. In the crystal, O—H⋯N, O—H⋯S, N—H⋯O and N—H⋯S hydrogen bonds link the molecules into sheets lying parallel to the bc plane. Aromatic π–π stacking interactions [centroid–centroid distances = 3.5078 (8)–3.6113 (8) Å] are also observed.

Data collection: APEX2 (Bruker, 2009); cell refinement: SAINT (Bruker, 2009); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL and PLATON (Spek, 2009  The 1,2,4-triazole nucleus has been incorporated into a wide variety of therapeutically interesting compounds. Several compounds containing 1,2,4-triazole rings are well known as drugs. For example, fluconazole is used as an antimicrobial drug (Shujuan et al., 2004), whereas vorozole, letrozole and anastrozole are non-steroidal drugs used for the treatment of cancer (Clemons et al., 2004) and loreclezole is used as an anticonvulsant (Johnston, 2002). Similarly substituted derivatives of triazole possess comprehensive bioactivities such as antimicrobial, anti-inflammatory, analgesic, antihypertensive, anticonvulsant and antiviral activities (Wei et al., 2007). We now report the synthesis and crystal structure of the title compound.

Experimental
A mixture of 2-(1-benzofuran-2-ylcarbonyl)hydrazinecarbothioamide (0.01 mol) and 10% KOH (10 ml) was refluxed for 3 h. The mixture was cooled to room temperature and then neutralized by the gradual addition of glacial acetic acid. The solid product obtained was collected by filtration, washed with ethanol and dried. It was then recrystallized using ethanol.
Yellow blocks of the title compound were obtained by slow evaporation of the ethanolic solution.

Figure 1
The molecular structure of the title compound, showing 50% probability displacement ellipsoids.

Figure 2
The crystal packing of the title compound, viewed down the b axis. The H atoms not involved in the intermolecular interactions (dashed lines) have been omitted for clarity.  (Cosier & Glazer, 1986) operating at 100.0 (1) K. Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes. 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.