N-(2,3-Dichlorophenyl)-2-nitrobenzenesulfonamide

In the title compound, C12H8Cl2N2O4S, the N—C bond in the C—SO2—NH—C segment has gauche torsions with respect to the S=O bonds. Further, the N—H bond is syn to the ortho-nitro group in the sulfonyl benzene ring and also syn to both the ortho- and meta-Cl atoms in the aniline ring. The molecule is twisted at the S—N bond with a torsion angle of 61.15 (18)°. The dihedral angle between the planes of the benzene rings is 68.00 (6)°. The amide H atom exhibits an intramolecular bifurcated N—H⋯(O,O) hydrogen bond. In the crystal, pairs of N—H⋯O(S) hydrogen bonds link the molecules into inversion dimers with R 2 2(8) motifs.

In the title compound, C 12 H 8 Cl 2 N 2 O 4 S, the N-C bond in the C-SO 2 -NH-C segment has gauche torsions with respect to the S O bonds. Further, the N-H bond is syn to the orthonitro group in the sulfonyl benzene ring and also syn to both the ortho-and meta-Cl atoms in the aniline ring. The molecule is twisted at the S-N bond with a torsion angle of 61.15 (18) . The dihedral angle between the planes of the benzene rings is 68.00 (6) . The amide H atom exhibits an intramolecular bifurcated N-HÁ Á Á(O,O) hydrogen bond. In the crystal, pairs of N-HÁ Á ÁO(S) hydrogen bonds link the molecules into inversion dimers with R 2 2 (8) motifs.

U. Chaithanya, Sabine Foro and B. Thimme Gowda Comment
As a part of studying the effect of substituents on the structures and other aspects of N-(aryl)-amides (Gowda et al., 1994); N-arylsulfonamides (Chaithanya et al., 2012;Gowda et al., 2002) and N-chloroarylsulfonamides , in the present work, the crystal structure of N-(2,3-dichlorophenyl)-2-nitrobenzenesulfonamide (I) has been determined ( Fig. 1). The conformation of the N-H bond is syn to the ortho-nitro group in the sulfonyl benzene ring and also syn to both the ortho-and meta-Cl atoms in the anilino ring, compared to the syn conformation between the N-H bond and the ortho-nitro group in the sulfonyl benzene ring and anti conformation between the N-H bond and the ortho-and meta-methyl groups in the anilino ring observed in N-(2,3-dimethylphenyl)-2nitrobenzenesulfonamide (II) (Chaithanya et al., 2012).
The molecule in (I) is twisted at the S-N bond with the torsion angle of 61.15 (18)°, compared to the values of -60.37 (30) and 58.81 (34)° in the two independent molecules of (II).
The dihedral angle between the sulfonyl and the anilino ring is 68.00 (6)°, compared to the values of 53.67 (8) and 56.99 (9)° in the two molecules of (II).
The amide H-atom showed bifurcated intramolecular H-bonding with the O-atom of the ortho-nitro group in the sulfonyl benzene ring, generating S(7) motifs and the intermolecular H-bonding with the sulfonyl oxygen atom of the other molecule, generating inversion dimers (Table 1, Fig. 2

Experimental
The title compound was prepared by treating 2-nitrobenzenesulfonylchloride with 2,3-dichloroaniline in the stoichiometric ratio and boiling the reaction mixture for 15 minutes. The reaction mixture was then cooled to room temperature and added to ice cold water (100 ml). The resultant solid N-(2,3-dichlorophenyl)-2-nitrobenzenesulfonamide was filtered under suction and washed thoroughly with cold water and dilute HCl to remove the excess sulfonylchloride and aniline, respectively. It was then recrystallized to constant melting point from dilute ethanol. The purity of the compound was checked and characterized by its infrared spectra.
Prism like colourless single crystals of the title compound used in X-ray diffraction studies were grown in ethanolic solution by slow evaporation of the solvent at room temperature.

Refinement
H atoms bonded to C were positioned with idealized geometry using a riding model with the aromatic C-H = 0.93 Å.
The amino H atom was freely refined with the N-H distance restrained to 0.86 (2) Å. All H atoms were refined with isotropic displacement parameters set at 1.2 U eq of the parent atom.  (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: PLATON (Spek, 2009); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).

Figure 1
The molecular structure of the title compound, showing the atom labelling scheme and with displacement ellipsoids drawn at the 50% probability level.

N-(2,3-Dichlorophenyl)-2-nitrobenzenesulfonamide
Crystal data 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.