N-[2-(9H-Carbazol-9-yl)ethyl]-4-(methylsulfonyl)aniline

In the title molecule, C21H20N2O2S, the dihedral angle between the mean plane of the carbazole ring system [maximum deviation = 0.021 (4) Å] and the benzene ring is 80.15 (6)°. In the crystal, molecules are linked by N—H⋯O and weak C—H⋯O hydrogen bonds into a C(8) chain along [001].

In the title molecule, C 21 H 20 N 2 O 2 S, the dihedral angle between the mean plane of the carbazole ring system [maximum deviation = 0.021 (4) Å ] and the benzene ring is 80.15 (6) . In the crystal, molecules are linked by N-HÁ Á ÁO and weak C-HÁ Á ÁO hydrogen bonds into a C(8) chain along [001].

Related literature
For a related structure, see: Lai et al. (2014) For the synthesis, see: Abdel-Magid et al. (1996); Hallberg et al. (1982). For hydrogen bond graph-set notation, see: Bernstein et al. (1995). Crystallographic data were collected through the SCrALS (Service Crystallography at Advanced Light Source) program at the Small-Crystal Crystallography Beamline 11.3.1 at the Advanced Light Source (ALS), Lawrence Berkeley National Laboratory. The ALS is supported by the US Department of Energy, Office of Energy Sciences Materials Sciences Division, under contract DE-AC02-05CH11231. We thank Dr Jeanette Krause of the University of Cincinnati and Dr Allen G. Oliver of the University of Notre Dame for the data collection.

Comment
Carbazole based compounds are important in drug discovery. As part of our ongoing effort to develop bioactive carbazole compounds (Lai et al., 2014), herein we report the crystal structure of the title compound (I). Compound (I) was obtained by reductive amination of carbazole-9-acetaldehyde through a direct procedure from Abdel-Magid et al. (1996).
Carbazole-9-acetaldehyde was synthesized according to the method of Hallberg et al. (1982). The molecular structure of (I) is shown in Fig.1. A portion of the unit cell shown in Fig. 2 illustrates how the molecules are linked by strong intermolecular N-H···O hydrogen bonds. These hydrogen bonds form a one-dimensional chain along [0 0 1] with a graph set descriptor of C(8) (Bernstein et al., 1995).

Experimental
All chemicals used were purchased from commercial sources and used without further purification. Carbazole-9acetaldehyde (2.09 g, 10 mmol) and 4-(methylsulfonyl)aniline (1.71 g, 10 mmol) were mixed in 1,2-dichloroethane (35 ml), followed by the addition of sodium triacetoxyborohydrate (2.97 g, 14 mmol). The reaction mixture was stirred at room temporature under a N 2 atmosphere for 12 h and then quenched by aqueous saturated NaHCO 3 . The resulted mixture was extracted with EtOAc, dried (MgSO 4 ) and concentrated to give the crude product as nearly colorless oil, which was further purified by column chromatography (Hexane/EtOAc 1/1) to provide white solid (2.89 g, 79%). This solid was characterized by NMR to be the title compound. Crystals were grown from MeOH/H 2 O (50:1 v/v) solution by slow evaporation.

Refinement
For the methyl group, the hydrogen atoms were added in calculated positions using a riding-model with C-H = 0.98 Å and U(H) = 1.5U eq (C). The torsion angle, which defines the orientation of the methyl group about the C-S bond, was refined. The hydrogen atom bonded to N2 was refined isotropically. The rest of the hydrogen atoms were included in the model in calculated positions using a riding-model with C-H = 0.95 to 0.99 Å and U(H) = 1.2U eq (C).  The molecular structure of (I) with displacement ellipsoids drawn at the 50% probability level (arbitrary spheres for the H atoms).

Figure 2
Crystal packing of (I) showing a portion of the unit cell emphasizing intermolecular N-H···O hydrogen bonds (dotted lines). Hydrogen atoms, except H(1N2), are omitted for clarity.

Special details
Experimental. Intensity data were collected at 150 K on a D8 goniostat equipped with a Bruker APEXII CCD detector at Beamline 11.3.1 at the Advanced Light Source (Lawrence Berkeley National Laboratory) using synchrotron radiation tuned to a wavelength of 0.7749 Angstroms. For data collection, frames were measured for a duration of 1 second using omega scans with a frame width of 0.3 degrees out to a maximum 2theta value of about 60 degrees. The data frames were collected using the program APEX2 and processed using the program SAINT within APEX2. The data were corrected for absorption and beam corrections based on the multi-scan technique as implemented in SADABS. Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes. Refinement. For the methyl group, the hydrogen atoms were added at calculated positions using a riding model with U(H) = 1.5 * U eq (bonded carbon atom). The torsion angle, which defines the orientation of the methyl group about the C-S bond, was refined. The hydrogen atom bonded to N(2) was refined isotropically. It is involved in an intermolecular hydrogen bond with atom O(2). The rest of the hydrogen atoms were included in the model at calculated positions using a riding model with U(H) = 1.2 * U eq (bonded atom).