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

There are two independent molecules in the asymmetric unit of the title compound, C14H14N2O4S. The N—H bonds are syn to the ortho-nitro groups in the sulfonyl benzene rings and anti to the methyl groups in the aniline benzene rings. The molecules are twisted at the S—N bonds with torsion angles of −60.4 (3) and 58.8 (3)° in the two molecules. The dihedral angles between the planes of the sulfonyl and the anilino benzene rings are 53.67 (8) and 56.99 (9)°. The amide H atoms of both molecules are involved in an intramolecular hydrogen bond, generating an S(7) motif. In the crystal, pairs of N—H⋯O(S) hydrogen bonds link like molecules into inversion dimers.

There are two independent molecules in the asymmetric unit of the title compound, C 14 H 14 N 2 O 4 S. The N-H bonds are syn to the ortho-nitro groups in the sulfonyl benzene rings and anti to the methyl groups in the aniline benzene rings. The molecules are twisted at the S-N bonds with torsion angles of À60.4 (3) and 58.8 (3) in the two molecules. The dihedral angles between the planes of the sulfonyl and the anilino benzene rings are 53.67 (8) and 56.99 (9) . The amide H atoms of both molecules are involved in an intramolecular hydrogen bond, generating an S(7) motif. In the crystal, pairs of N-HÁ Á ÁO(S) hydrogen bonds link like molecules into inversion dimers.
The asymmetric unit of the structure contains two independent molecules. The conformation of the N-H bonds are syn to the ortho-nitro groups in the sulfonyl benzene rings and anti to both the ortho-and meta-methyl groups in the anilino rings, compared to a syn conformation between the N-H bonds and the ortho-nitro groups in the sulfonyl benzene rings or the ortho-methyl group in the anilino ring observed in N-(2-methylphenyl)-2-nitrobenzenesulfonamide (II) (Chaithanya et al., 2012). In (I) the molecules are twisted at the S-N bonds with the torsional angles of -60.37 (30) and 58.81 (34)°, compared to the value of 73.90 (26)° in (II). The dihedral angles between the sulfonyl and anilino rings are 53.67 (8) and 56.99 (9)°, compared to the value of 53.44 (14)° in (II).
The amide H-atoms each form intramolecular H-bonds with the O3 and O7 atoms of the ortho-nitro groups in the sulfonyl benzene rings, generating S(7) motifs (Bernstein et al., 1995). Intermolecular H-bonds from amide H-atoms to sulfonyl oxygen atoms of a similar neighbouring molecule, generate R 2 2 (8) inversion dimers (Table 1, Fig. 2.)

Experimental
The title compound was prepared by treating 2-nitrobenzenesulfonylchloride with 2,3-dimethylaniline 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-dimethylphenyl)-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 (138° C) from dilute ethanol. The purity of the compound was checked and characterized by its infrared spectrum.
Prism like light pink 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, methyl C-H = 0.96 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 (C-aromatic, N) and 1.5 U eq (C-methyl)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). Crystal packing of the title compound with hydrogen bonds shown as dashed lines.  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.