3-[(5-Chloro-2-hydroxybenzylidene)amino]-2-sulfanylidene-1,3-thiazolidin-4-one

In the title compound, C10H7ClN2O2S2, the mean plane of the thioxothiazolidine ring [maximum deviation = 0.032 (2) Å] is inclined to the benzene ring by 12.25 (4)°. There is a strong intramolecular O—H⋯N hydrogen bond present. In the crystal, molecules are linked via pairs of C—H⋯Cl hydrogen bonds, forming inversion dimers.

In the title compound, C 10 H 7 ClN 2 O 2 S 2 , the mean plane of the thioxothiazolidine ring [maximum deviation = 0.032 (2) Å ] is inclined to the benzene ring by 12.25 (4) . There is a strong intramolecular O-HÁ Á ÁN hydrogen bond present. In the crystal, molecules are linked via pairs of C-HÁ Á ÁCl hydrogen bonds, forming inversion dimers.

Related literature
For general background to the chemistry, and pharmacological and biological activity of rhodanine and its derivatives, see: Raper (1985); Contello et al. (1994); Villain-Guillot et al.   Table 1 Hydrogen-bond geometry (Å , ).  Rhodanine and its derivatives are used in a variety of applications ranging from industry to biochemistry and coordination chemistry. They have wide industrial applications as brightening additives in silver electroplating, intermediates in the syntheses of dyes, extreme-pressure lubricants and antioxidants as well as pharmacological (Contello et al., 1994), and biological activities including antibacterial (Villain-Guillot et al., 2007), antiviral (Yan et al., 2007) and antidiabetical (Kletzien et al., 1992). The interesting aspect of the chemistry of these compounds is their electron donating power to metal ions, which make them strong ligands in coordination compounds (Raper, 1985). herein we report on the crystal structure of the title rhodanine derivative.
In the crystal, molecules are linked via a pair of C-H···Cl hydrogen bonds forming inversion dimers (Table 1).

Experimental
The title compound was prepared by the reaction of 2-hydroxy-5-chlorophenyl (0.63 g, 4 mmol) and N-amino rhodanine (0.50 g, 4 mmol) in methanol (50 ml) at room temperature. After stirring for 6 h, a fluffy yellow precipitate was obtained.
The resulting crude solid was collected by filtration, dried and then purified by repeated recrystallization using methanol as solvent; yielding yellow block-like crystals.

Refinement
Atoms H2 (for OH) and H7 (for methine) were located in a difference Fourier map and refined freely. The C-bound Hatoms were positioned geometrically with C-H = 0.95 and 0.99 Å for aromatic and methylene H-atoms, respectively, and constrained to ride on their parent atoms, with U iso (H) = 1.2 × U eq (C).  The molecular structure of the title molecule, with atom labelling. Displacement ellipsoids are drawn at the 50% probability level. The intramolecular O-H···N hydrogen bond is shown as a dashed line -see Table 1 for details. Special details Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds 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 > 2sigma(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.