Crystal structures of isomeric 3,5-dichloro-N-(2,3-dimethylphenyl)benzenesulfonamide, 3,5-dichloro-N-(2,6-dimethylphenyl)benzenesulfonamide and 3,5-dichloro-N-(3,5-dimethylphenyl)benzenesulfonamide

In the isomeric title compounds, N—H⋯O and C—H⋯O hydrogen bond, and C—H⋯π and π–π interactions build different supramolecular architectures.


Chemical context
Sulfonamide drugs were the first chemotherapeutic agents to be used for curing and preventing bacterial infection in human beings (Shiva Prasad et al., 2011). They play a vital role as key constituents in a number of biologically active molecules and are known to exhibit a wide variety of biological activities, such as antibacterial (Subhakara Reddy et al., 2012;Himel et al., 1971), antifungal (Hanafy et al., 2007), anti-inflammatory (Kü çü kgü zel et al., 2013), antitumor ), anticancer (Al-Said et al., 2011, anti-HIV (Sahu et al., 2007) and antitubercular activities (Vora & Mehta, 2012). In recent years, extensive research studies have been carried out on the synthesis and evaluation of the pharmacological properties of molecules containing the sulfonamide moiety, which have been reported to be important pharmacophores (Mohan et al., 2013).
With these considerations in mind and based on our structural study of 3,5-dichloro-N-(substitutedphenyl)benzenesulfonamides

Supramolecular features
The crystal structure of (I) features inversion-related dimers linked by N1-H1Á Á ÁO2 i hydrogen bonds forming R 2 2 (8) loops (Fig. 4, Table 1). The R 2 2 (8) loops are interconnected via C(7) chains of C4-H4Á Á ÁO1 ii intermolecular interactions, forming a three-dimensional supramolecular architecture. The structure also featuresinteractions involving the benzenesulfonyl ring and the aniline ring as illustrated in Fig The molecular structure of (I) with displacement ellipsoids drawn at the 50% probability level.

Figure 3
The molecular structure of (III) with displacement ellipsoids drawn at the 50% probability level.

Figure 2
The molecular structure of (II) with displacement ellipsoids drawn at the 50% probability level. Intramolecular C-HÁ Á ÁO and C-HÁ Á Á hydrogen interactions are shown as dotted lines.

Figure 5
Partial crystal packing of (II) showing the formation of a one-dimensional architecture through N-HÁ Á ÁO hydrogen bonds andinteractions (thin blue dotted lines). Table 3 Hydrogen-bond geometry (Å , ) for (III).

Synthesis and crystallization
The title compounds were prepared according to a literature method (Rodrigues et al., 2015). The purities of all the compounds were checked by determining their melting points. Colourless prismatic single crystals suitable for X-ray diffraction studies were obtained by slow evaporation of ethanolic solutions of the compounds at room temperature.

Refinement details
Crystal data, data collection and structure refinement details are summarized in Table 4. The amino H atoms were located in difference-Fourier maps and refined isotropically with the N-H bond length restrained to be 0.88 (2) Å . All other H atoms were positioned geometrically and refined as riding with C-H = 0.95-0.98 Å and U iso (H) = 1.2 or 1.5U eq (C). A rotating model was applied to the methyl groups. To improve considerably the values of R1, wR2, and S (goodness-of-fit), a lowangle reflection partially obscured by the beam-stop (100) was omitted from the final refinement of (III). Partial crystal packing of (III) viewed down the c axis displaying twodimensional sheets. Thin blue dotted lines denote N-HÁ Á ÁO hydrogen bonds and C-HÁ Á Á interactions. H atoms not involved in hydrogen bonding are omitted for clarity.

Figure 7
Crystal packing of (III) viewed approximately along the a axis, showing theinteractions (black dotted lines) between adjacent sheets. For clarity, only H atoms involved in N-HÁ Á ÁO hydrogen bonds and C-HÁ Á Á interactions (thin blue dotted lines) are included.  APEX2 (Bruker, 2009) and SAINT-Plus (Bruker, 2009); data reduction: SAINT-Plus (Bruker, 2009) and XPREP (Bruker, 2009); program(s) used to solve structure: SHELXT 2016/4 (Sheldrick, 2015a); program(s) used to refine structure: SHELXL2016/4 (Sheldrick, 2015b); molecular graphics: Mercury (Macrae et al., 2008); software used to prepare material for publication: SHELXL2016/4 (Sheldrick, 2015b). 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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )
x y z U iso */U eq C1 0.8417 (4) 0.5358 (5)  where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max = 0.001 Δρ max = 0.82 e Å −3 Δρ min = −0.88 e Å −3 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.