2,4-Dichloro-N-(4-chlorophenyl)benzenesulfonamide

The molecule of the title compound, C12H8Cl3NO2S, is twisted at the S atom, the C—SO2—NH—C torsion angle being 67.8 (2)°. The dihedral angle between the two benzene rings is 65.0 (1)°. The crystal structure features inversion dimers linked by pairs of N—H⋯O hydrogen bonds.

The molecule of the title compound, C 12 H 8 Cl 3 NO 2 S, is twisted at the S atom, the C-SO 2 -NH-C torsion angle being 67.8 (2) . The dihedral angle between the two benzene rings is 65.0 (1) . The crystal structure features inversion dimers linked by pairs of N-HÁ Á ÁO hydrogen bonds.

Related literature
For the preparation of the title compound, see: Savitha & Gowda (2006). For our study of the effect of substituents on the structures of N-(aryl)arylsulfonamides, see: Gowda et al. (2009Gowda et al. ( , 2010 Table 1 Hydrogen-bond geometry (Å , ).

Comment
In the present work, as part of a study of substituent effects on the structures of N-(aryl)arylsulfonamides (Gowda et al., 2009(Gowda et al., , 2010, the structure of 2,4-dichloro-N-(4-chlorophenyl)benzenesulfonamide (I) has been determined (Fig. 1). The In the crystal structure, the pairs of intermolecular N-H···O hydrogen bonds (Table 1) link the molecules to form inversion-related dimers as shown in Fig. 2.

Experimental
The solution of 1,3-dichlorobenzene (10 ml) in chloroform (40 ml) was treated drop-wise with chlorosulfonic acid (25 ml) at 273 K. After the initial evolution of hydrogen chloride subsided, the reaction mixture was brought to room temperature and poured into crushed ice in a beaker. The chloroform layer was separated, washed with cold water and allowed to evaporate slowly. The residual 2,4-dichlorobenzenesulfonylchloride was treated with a stoichiometric amount of p-chloroaniline and boiled for ten minutes. The reaction mixture was then cooled to room temperature and added to ice cold water (100 ml).
The resultant solid 2,4-dichloro-N-(4-chlorophenyl)benzenesulfonamide was filtered under suction and washed thoroughly with cold water. It was then recrystallized to constant melting point from dilute ethanol. The purity of the compound was checked and characterized by recording its infrared and NMR spectra (Savitha & Gowda, 2006). The single crystals used in X-ray diffraction studies were grown in ethanolic solution by slow evaporation at room temperature.

Refinement
The H atom of the NH group was located in a difference map and refined with the distance restraint N-H = 0.86 (2) Å. The other H atoms were positioned with idealized geometry using a riding model [C-H = 0.93 Å]. All H atoms were refined with isotropic displacement parameters (set to 1.2 times of the U eq of the parent atom).
supplementary materials sup-2 Figures   Fig. 1. Molecular structure of (I), showing the atom-labelling scheme. Displacement ellipsoids are drawn at the 50% probability level.

Data collection
Oxford Diffraction Xcalibur single-crystal X-ray diffractometer with a Sapphire CCD detector 2873 independent reflections

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 > 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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )
x y z U iso */U eq C1 0.2300 (