N-(1,3-Thiazol-2-yl)-N′-[(thiophen-2-yl)carbonyl]thiourea hemihydrate

The title compound, C9H7N3OS3·0.5H2O, crystallizes with two independent but similar molecules in the asymmetric unit, both of which are linked by a water molecule through O—H⋯N hydrogen bonds. In addition the water O atom is further linked by N—H⋯O hydrogen bonds to two additional main molecules, forming a tetrameric unit. These tetrameric units then form infinite ribbons parallel to the ac plane.The dihedral angle between the thiophenoyl and thiazolyl rings is 12.15 (10) and 21.69 (11)° in molecules A and B, respectively. The central thiourea core makes dihedral angles of 5.77 (11) and 8.61 (9)°, respectively, with the thiophenoyl and thiazolyl rings in molecule A and 8.41 (10) and 13.43 (12)° in molecule B. Each molecule adopts a trans–cis geometry with respect to the position of thiophenoyl and thiazole groups relative to the S atom across the thiourea C—N bonds. This geometry is stabilized by intramolecular N—H⋯O hydrogen bonds.

ligand atom and plays an important role in coordination chemistry with transition metals. These compounds are found to be useful in heterocyclic synthesis and many of these substrates have interesting biological activities (Aly et al., 2007).
The title compound ( Fig. 1), C 9 H 7 N 3 OS 3 .0.5H 2 O, crystallizes with two independent but similar molecules in the asymmetric unit both of which are linked by a water molecule through O-H···N hydrogen bonds. In addition the water O is further linked by N-H···O hydrogen bonds to two additional C 9 H 7 N 3 OS 3 molecules, forming a tetrameric moiety. These tetrameric moieties then form infinite ribbons parallel to the ac plane (Fig.2).
The main bond lengths and angles are within the range obtained for similar compounds (Koch et al., 2001;Perez et al., 2008).  Table 1).

Experimental
A solution of 2-thiophenecarbonyl chloride (0.01 mol) in anhydrous acetone (80 ml) was added dropwise to a suspension of ammonium thiocyanate (0.01 mol) in anhydrous acetone (50 ml) and the reaction mixture was refluxed for 50 minutes.
After cooling to room temperature, a solution of 4-chloroaniline (0.01 mol) in dry acetone (25 ml) was added and the resulting mixture refluxed for 2 h. The reaction mixture was poured into five times its volume of cold water, upon which the thiourea precipitated. The product was recrystallized from ethanol as colorless block crystals.

Refinement
Hydrogen atoms on the water molecule were located in a difference-Fourier map and both positional and isotropic displacement parameters were refined. Other H atoms were placed in calculated positions with N-H = 0.88 Å and C-H = 0.95 Å and refined using a riding model, with U iso (H) = 1.2U eq (C, N).

Special details
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.