2-[(2-Carboxyphenyl)sulfanyl]acetic acid

The title compound, C9H8O4S, affords a zigzig chain in the crystal structure by intermolecular O—H⋯O hydrogen bonds. The molecular geometry suggests that extensive but not uniform π-electron delocalization is present in the benzene ring and extends over the exocyclic C—S and C—C bonds.

The title compound, C 9 H 8 O 4 S, affords a zigzig chain in the crystal structure by intermolecular O-HÁ Á ÁO hydrogen bonds. The molecular geometry suggests that extensive but not uniform -electron delocalization is present in the benzene ring and extends over the exocyclic C-S and C-C bonds.
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: AT2858). of the rigid carboxylate system may facilitate the formation of inorganic-organic materials with high thermal stability and form large channels, while the peculiar coordination chemistry of the flexible carboxylate system employed in the self-assembly reaction has versatile coordination behavior and may be favorable for the formation of the helical structure (Sagatys et al., 2003;Sokolov et al., 2001). As shown in Fig.1, the bond lengths within the benzene ring exhibit the expected pattern with C-C bonds (1.368 (8)-1.399 (6) Å) between the single and double bonds. And the bond distance of C1-C7 (1.476 (5) Å) and S1-C6 (1.768 (4) Å) also fall between the double and single bonds. All these interatomic distances suggest that extensive but not uniform π electron delocalization is present in the benzene ring and extends over the exocyclic C-S and C-C bonds. The torsion angle of C6-S1-C8-C9 is -71.7 (4)°. O-H···O hydrogen bonds link independent molecules to form a zigzig chain.

Experimental
To an aqueous solution of 2-thiobenzoic acid (1.54 g, 10.0 mmol) and NaOH (0.80 g, 20.0 mmol) were sequentially added the aqueous solution of chloroactic acid (2.835 g, 30.0 mmol) and NaOH (1.400 g, 35.0 mmol). After stirring for 4 h at 353 K under nitrogen atmosphere, the mixture was cooled to room temperature slowly. Adjusted the pH to 2 by adding 1.0 mol/L HCl, the pink deposit appeared rapidly. The solids were filtered and washed with water. The single crystals suitable for X-ray diffraction were obtained by the recrystallization of sieved solid in the ethanol.

Refinement
The H atoms bonded to C atoms were positioned geometrically [aromatic C-H = 0.93 Å and aliphatic C-H = 0.97 Å, U iso (H) = 1.2U eq (C)]. The H atoms bonded to O atoms were located in a difference Fourier map and refined freely. Fig. 1

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 Rfactors(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.