9-(4-Nitrophenylsulfonyl)-9H-carbazole

In the title molecule, C18H12N2O4S, the carbazole skeleton is nearly planar [maximum deviation = 0.037 (1) Å] and is oriented at a dihedral angle of 73.73 (5)° with respect to the benzene ring. An intramolecular C—H⋯O hydrogen bond links a nitro O atom to the carbazole skeleton. In the crystal, intermolecular C—H⋯O hydrogen bonds link the molecules into a three-dimensional network. π–π contacts between inversion-related benzene rings [centroid–centroid distance = 3.7828 (8) Å] and two weak C—H⋯π interactions may also stabilize the structure.

In the title molecule, C 18 H 12 N 2 O 4 S, the carbazole skeleton is nearly planar [maximum deviation = 0.037 (1) Å ] and is oriented at a dihedral angle of 73.73 (5) with respect to the benzene ring. An intramolecular C-HÁ Á ÁO hydrogen bond links a nitro O atom to the carbazole skeleton. In the crystal, intermolecular C-HÁ Á ÁO hydrogen bonds link the molecules into a three-dimensional network.contacts between inversion-related benzene rings [centroid-centroid distance = 3.7828 (8) Å ] and two weak C-HÁ Á Á interactions may also stabilize the structure.

Comment
Tetrahydrocarbazole systems are present in the framework of a number of indole-type alkaloids of biological interest (Saxton, 1983). The structures of tricyclic, tetracyclic and pentacyclic ring systems with dithiolane and other substituents of the tetrahydrocarbazole core, have been reported previously (Hökelek et al., 1994;Patır et al., 1997;Hökelek et al., 1998;Hökelek et al., 1999;Hökelek & Patır, 1999). Carbazole-based compounds play a very important role in electroactive materials (Morin et al., 2004;Pasquali et al., 1993). Carbazole-based heterocyclic polymer systems can be chemically or electrochemically polymerized to give products with a number of applications, such as rechargable batteries (Sacak, 1999) and electrochromic displays (Santhanam & Sundaresan, 1986). The title compound may be considered as a synthetic precursor of tetracyclic indole alkaloids of biological interests. The present study was undertaken to ascertain its crystal structure.
The title compound consists of a carbazole skeleton with a nitrophenylsulfonyl group (Fig. 1), where the bond lengths and angles are within normal ranges, and generally agree with those in the previously reported compounds mentioned above.
In all structures atom N9 is substituted.

Experimental
For the preparation of the title compound, carbazole (3.0 g, 19.45 mmol) and 4-nitrobenzene-1-sulfonyl chloride (8.6 g, 38.91 mmol) were dissolved in dichloromethane (300 ml), and then tetramethyl ammonium hydrogen sulphate (0.3 g) and sodium hydroxide (40 ml, 50%) were added. The resulting mixture was stirred at room temperature for 24 h. It was then poured into water (200 ml) and dichloromethane (200 ml). The solvent was evaporated and the residue was purified by column chromatograpy using silica gel, and the product was crystallized from ethylacetate (yield; 4.2 g, 75.12%, m.p. 466 K).
supplementary materials sup-2 Refinement H atoms were positioned geometrically with C-H = 0.95 Å for aromatic H atoms, and constrained to ride on their parent atoms, with U iso (H) = 1.2U eq (C). Fig. 1. The molecular structure of the title molecule with the atom-numbering scheme. The displacement ellipsoids are drawn at the 50% probability level.  Table 1 for details].

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 > 2sigma(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.