N,N-Diethyl-2-(4-methylbenzenesulfonamido)benzamide

The asymmetric unit of the title compound, C18H22N2O3S, contains two molecules, exhibiting similar conformations [C—S—N—C torsion angles of −82.2 (2) and −70.4 (2)°, and dihedral angles between the mean planes of the aromatic rings of 56.6 (6) and 51.6 (6)° in molecules I and II, respectively]. However, the two independent molecules show distinctly different hydrogen-bonding patterns. In the crystal, molecules I form inversion dimers via pairs of N—H⋯O hydrogen bonds, whereas for molecules II the N—H⋯O hydrogen bond is intramolecular. The hydrogen-bonded dimers of I further propagate along the b-axis direction through π–π interactions [the distance between ring centroids is 3.8424 (8) Å].

The asymmetric unit of the title compound, C 18 H 22 N 2 O 3 S, contains two molecules, exhibiting similar conformations [C-S-N-C torsion angles of À82.2 (2) and À70.4 (2) , and dihedral angles between the mean planes of the aromatic rings of 56.6 (6) and 51.6 (6) in molecules I and II, respectively]. However, the two independent molecules show distinctly different hydrogen-bonding patterns. In the crystal, molecules I form inversion dimers via pairs of N-HÁ Á ÁO hydrogen bonds, whereas for molecules II the N-HÁ Á ÁO hydrogen bond is intramolecular. The hydrogen-bonded dimers of I further propagate along the b-axis direction throughinteractions [the distance between ring centroids is 3.8424 (8) Å ].
Data collection: CrysAlis CCD (Oxford Diffraction, 2006); cell refinement: CrysAlis CCD; data reduction: CrysAlis RED (Oxford Diffraction, 2006); program(s) used to solve structure: SIR97 (Altomare et al., 1999); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 (Farrugia, 1997); software used to prepare material for publication: SHELXL97, WinGX (Farrugia, 1999) and PARST (Nardelli, 1995). (Lu & Tucker, 2007), antimicrobial drugs (Tappe et al., 2008, carbonic anhydrase inhibitors (Chegwidden et al., 2000), and anti-tumor agents (Purushottamachar et al., 2008). Because the structural and conformational properties of a compound usually are related to its biological properties, their study would provide useful information to design new effective drugs. In this regard, there are many recent publications reporting structural data on related sulfonamides (Parkin et al., 2008, Altamura et al., 2009, Perlovich et al., 2009, Perlovich et al., 2011,Vega-Hissi et al., 2011. The asymmetric unit of the title compound contains two independent molecules, I and II, which are almost superimposable ( Table 1). As expected, a staggered conformation about the N-S bond is adopted, with the N lone pair bisecting the OŜO angle, and with the p orbital at the ipso carbon bisecting the same angle (Table 1, Fig. 1). The sulfonamide nitrogen atom is almost planar-trigonal in molecule I (Σ<N=355 (1)°), while in II it is definitely more pyramidal (Σ<N=341 (1)°). The conformation of molecule II is stabilized by an intramolecular H-bond involving the H atom of the sulfonamide grouping (HN1′) and the oxygen atom O3′ of the amide moiety (Table 2). In the crystal packing, molecules I form dimers instead, which are held together by a couple of N-H···O=C hydrogen bonds (Table 2, Fig. 2).

Refinement
The N-H H atoms were located in the Fourier difference map and their coordinates were refined with U iso (H) = 1.2U eq (N). All other H atoms were positioned using idealized geometry, and refined using a riding model with U iso (H) 1.2 times U eq (C) (1.5 for methyl H atoms).  The symmetrically independent molecule I (molecule II has a similar shape and the same labelling scheme).

Computing details
Displacement ellipsoids are drawn at the 30% probability level.

Figure 2
Crystal structure of the title compound as viewed along the a-axis (molecules I are shown in blue and molecules II -in red). Intermolecular NH···O hydrogen bonding is shown as dashed lines.

N,N-Diethyl-2-(4-methylbenzenesulfonamido)benzamide
Special details Geometry. All s.u.'s (except the s.u. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell s.u.'s are taken into account individually in the estimation of s.u.'s in distances, angles and torsion angles; correlations between s.u.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell s.u.'s is used for estimating s.u.'s 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 > 2σ(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.