Crystal structures of 1-benzenesulfonyl-2-methyl-3-(4-nitrobenzoyl)-2,3-dihydro-1H-indole and 1-benzenesulfonyl-2-methyl-3-[(thiophen-2-yl)carbonyl]-2,3-dihydro-1H-indole

In the title indole derivatives, the sulfonyl-bound phenyl rings are almost orthogonal to the indole ring system, subtending dihedral angles of 88.33 (10) and 87.58 (16)°, respectively. The molecules of both (I) and (II) feature intramolecular C—H⋯O hydrogen bonds that generate S(6) ring motifs with the sulfone O atom. In the crystals, molecules of (I) are linked by C—H—O hydrogen bonds, forming (18) ring motifs while molecules of (II) are linked by C—H—O and C—H—S hydrogen bonds, forming (12) ring motifs.


Chemical context
Indole is the parent compound of a large number of important compounds in nature with significant biological activity (Kaushik et al., 2013). Indole derivatives are known to exhibit anti-bacterial, anti-fungal (Singh et al., 2000), anti-tumour (Andreani et al., 2001), antidepressant (Grinev et al., 1984), anti-inflammatory (Rodriguez et al., 1985) and physiological (Porter et al., 1977;Sundberg, 1996) properties. They are used as bioactive drugs (Stevenson et al., 2000) and have also been proven to display high aldose reductase inhibitory (Rajeswaran et al., 1999) and antimicrobial activities (Amal Raj et al., 2003). Indole derivatives containing a phenylsulfonyl group exhibit insecticidal, germicidal and fungicidal activity (Wolf, 1999). Against this background, the crystal structure determination of the title compounds was carried out to study their structural aspects and the results are presented here.
The sum of the bond angles around N1 is 358.4 , indicating sp 2 hybridization.
In both compounds, the indole moiety is essentially planar with a maximum deviation of 0.021 (2) Å for both atom C10 in compound (I) and atom C8 in compound (II). In both compounds, the variation in endocyclic angles [119.05 (16) at C12 and 122.17 (17) at C7 for compound (I) and 119.7 (3) at C6 and 121.5 (3) at C1 for compound (II)] of the benzene ring of the indole ring system are due to the fusion of the five-and six -membered rings and the strain is taken up by the angular distortion rather than by bond-length distortion (Allen et al., 1987).

Figure 4
The crystal packing of compound (II) viewed along the b axis, showing the intermolecular C2-H2-O2 and C14-H14B-S2 hydrogen bonds as dashed lines. Symmetry codes are as in Table 2. motifs (two-dimensional network). No significantor C-HÁ Á Á interactions are observed in either compound.

Synthesis and crystallization
Compound (I) To a solution of 4-nitrobenzoyl chloride (2.06 g, 11.07 mmol) in dry DCM (15 ml) at 273 K, SnCl 4 (2.06 g, 11.07 mmol) was added slowly (5 min). To this, a solution of 1-phenylsulfonyl-2-methylindole (2 g, 7.38 mmol) in dry DCM (10 ml) was added (5 min) and allowed to stir at room temperature for 48 h. After completion of the reaction (monitored by TLC), it was poured into ice-water (50 ml) containing conc. HCl (10 ml). The organic layer was separated and the aqueous layer was extracted with DCM (2 Â 20 ml). The combined organic layer was washed with water (3 Â 25 ml) and dried (Na 2 SO 4 ). The subsequent purification of the crude product either by washing with MeOH or column chromatography (silica gel, hexane:ethyl acetate 8:2) furnished the first title compound as a colourless solid (1.92 g, 62%); m.p. 435-437 K.

Compound (II)
To a solution of thiophene-2-carbonyl chloride (1.63 g, 11.07 mmol) and SnCl 4 (2.88 g, 11.07 mmol) in dry DCM (20 ml) at 273 K, a solution of 1-phenylsulfonyl-2-methylindole (2 g, 7.38 mmol) in dry DCM (10 ml) was added slowly (5 min). Then, it was stirred at room temperature for 30 min. After completion of the reaction (monitored by TLC), it was poured into ice-water (50 ml) containing conc. HCl (10 ml). The organic layer was separated and the aqueous layer was extracted with DCM (2 Â 20 ml). The combined organic extract was washed with water (3 Â 25 ml) and dried (Na 2 SO 4 ). Evaporation of the solvent followed by trituration of the crude product with MeOH (5 ml) gave the second title compound as a colourless solid (2.19 g, 78%); m.p. 379-381 K.

Refinement
Crystal data, data collection and structure refinement details are summarized in Table 3. H atoms were localized from the difference electron-density maps and refined as riding atoms with C-H = 0.93 or 0.97 Å with U iso (H) = 1.5U eq (C) for methyl H atoms and 1.2U eq (C) for other H atoms. Compound (II) was refined as an inversion twin (BASF 0.03). program(s) used to refine structure: SHELXL2014/7 (Sheldrick, 2015b); molecular graphics: ORTEP-3 for Windows (Farrugia, 2012) and Mercury (Macrae et al., 2008); software used to prepare material for publication: SHELXL2014/7 (Sheldrick, 2015b).  where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max < 0.001 Δρ max = 0.45 e Å −3 Δρ min = −0.39 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.

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. Refined as a 2-component inversion twin.