Crystal structures of three N-(arylsulfonyl)-4-fluorobenzamides

The crystal structures of three N-(arylsulfonyl)-4-fluorobenzamides, namely 4-fluoro-N-(2-methylphenylsulfonyl)benzamide, (I), N-(2-chlorophenylsulfonyl)-4-fluorobenzamide, (II), and N-(4-chlorophenylsulfonyl)-4-fluorobenzamide monohydrate, (III), are described and compared with related structures. The conformation of the three molecules is very similar with the aromatic rings being inclined to one another by 82.83 (11) and 85.01 (10)° in the two independent molecules of (I), 89.91 (10)° in (II) and 81.82 (11)° in (III).

The crystal structures of three N-arylsulfonyl-4-fluorobenzamides, namely 4-fluoro-N-(2-methylphenylsulfonyl)benzamide, C 14 H 12 FNO 3 S, (I), N-(2chlorophenylsulfonyl)-4-fluorobenzamide, C 13 H 9 ClFNO 3 S, (II), and N-(4chlorophenylsulfonyl)-4-fluorobenzamide monohydrate, C 13 H 9 ClFNO 3 SÁH 2 O, (III), are described and compared with related structures. The asymmetric unit of (I) contains two independent molecules (A and B), while that of (II) contains just one molecule, and that of (III) contains a molecule of water in addition to one main molecule. The dihedral angle between the benzene rings is 82.83 (11) in molecule A and 85.01 (10) in molecule B of (I), compared to 89.91 (10) in (II) and 81.82 (11) in (III). The crystal structure of (I) features strong N-HÁ Á ÁO hydrogen bonds between the A and B molecules, resulting in an R 4 4 (16) tetrameric unit. These tetrameric units are connected into sheets in the bc plane by various C-HÁ Á ÁO interactions, and adjacent sheets are further interlinked via C-HÁ Á Á aryl interactions, forming a three-dimensional architecture. The crystal structure is further stabilized by arylaryl and S OÁ Á Á aryl interactions. In the crystal of (II), molecules are connected into R 2 2 (8) and R 2 2 (14) dimers via N-HÁ Á ÁO hydrogen bonds and C-HÁ Á ÁO interactions, respectively; the dimers are further interconnected via a weak C OÁ Á Á aryl interaction, leading to the formation of chains along [110]. In the crystal of (III), N-HÁ Á ÁO and O-HÁ Á ÁO hydrogen bonds involving both the main molecule and the solvent water molecule results in the formation of sheets parallel to the bc plane. The sheets are further connected by C-HÁ Á ÁO interactions and weak C-ClÁ Á Á aryl , C-FÁ Á Á aryl and S OÁ Á Á aryl interactions, forming a three-dimensional architecture.

Chemical context
Sulfonamide and amide moieties play a very significant role as key constituents in a number of biologically active molecules Manojkumar et al., 2013;Hamad & Abed, 2014). In recent years, N-(arylsulfonyl)arylamides have received much attention as they constitute an important class of drugs for Alzheimer's disease (Hasegawa & Yamamoto, 2000), as well as antibacterial inhibitors of tRNA synthetases (Banwell et al., 2000), antagonists for angiotensin II (Chang et al., 1994) and leukotriene D4-receptors (Musser et al., 1990). Further, N-(arylsulfonyl)arylamides are known to be potent anti-tumour agents against a broad spectrum of human tumour xenografts (colon, lung, breast, ovary and prostate) in nude mice (Mader et al., 2005). In view of the importance of N-(arylsulfonyl)arylamides, the title compounds, (I), (II) and (III), were synthesized and we report herein on their crystal structures. ISSN 2056-9890

Structural commentary
The asymmetric unit of compound (I) contains two independent molecules (A and B) (Fig. 1), that differ slightly in their molecular conformations. The asymmetric unit of compound (II) (Fig. 2) contains one molecule, while compound (III) (Fig. 3) crystallizes as a water monosolvate. In molecules A and B of (I), the ortho-methyl substituent on the benzenesulfonyl ring is syn to the N-H bond in the central -C-SO 2 -N-C(O)-segment ( Fig. 1). This is similar to the syn confor-mation observed for the N-H bond in the central -C-SO 2 -N-C(O)-segment with respect to the ortho-chloro substitution on the benzenesulfonyl ring of (II). The dihedral angle between the benzene rings is 82.83 (11) in molecule A and 85.01 (10) in molecule B of (I), compared to 89.91 (10) in (II) and 81.82 (11) in (III). Further, in (I) the dihedral angles between the benzoic acid ring and the central C8-C7(O3)-N1-S1 segment are 28.99 (1) and 23.81 (9) in molecules A and B, respectively, while it is 10.41 (10) in (II) and 21.23 (10) in (III). The dihedral angles between the sulfonamide ring and the C7(O3)-N1-S1-C1 segment are, respectively, 68.67 (12) and 77.31 (10) in molecules A and B of (I). The corresponding dihedral angle in (II) is 70.77 (11) , whereas in (III) the value is much less, viz 48.03 (12) . An intramolecular C14B--H14BÁ Á ÁO2B hydrogen bond ( Fig.1 and Table 1) is observed in molecule B of (I), with an S(6) ring motif.

Supramolecular features
The crystal structure of (I), features two strong N-HÁ Á ÁO hydrogen bonds, namely, N1A-H1AÁ Á ÁO1B and N1B-H1BÁ Á ÁO1A hydrogen bonds (Table 1) between the A and B molecules, resulting in a tetrameric unit (Fig. 4). The unitary level graph-set notation for each hydrogen bond is D(2), while in the second level the tetrameric unit has a graph-set motif of R 4 4 (16). Adjacent tetramers are connected into sheets in the bc plane (Fig. 4)  A view of the molecular structure of the two independent molecules (A and B) of compound (I), with atom labelling. Displacement ellipsoids are drawn at the 50% probability level.

Figure 2
A view of the molecular structure of compound (II), with atom labelling. Displacement ellipsoids are drawn at the 50% probability level.

Figure 3
A view of the molecular structure of compound (III), with atom labelling. Displacement ellipsoids are drawn at the 50% probability level. and C10B-H10BÁ Á ÁO3B interactions (Table 1). Adjacent sheets are further interconnected via C4B-H4BÁ Á Á aryl interactions (involving the centroid of the fluorobenzoyl ring of molecule B) ( Fig. 5 and Table 1) to form chains along the a axis, so forming a three-dimensional architecture. The crystal structure of (I), is further stabilized by arylaryl interactions ( Fig. 6)  Crystal packing of (I), displaying N-HÁ Á ÁO hydrogen bonds and C-HÁ Á ÁO intermolecular interactions (dashed lines), which result in the formation of sheets parallel to the bc plane. interactions (dashed lines) displayed in (I).

Figure 8
Crystal packing of (III), displaying an infinite two-dimensional sheet parallel to the bc plane formed via N-HÁ Á ÁO and various O-HÁ Á ÁO hydrogen bonds (dashed lines).
Series 2: The asymmetric units of all of the compounds in series 2 (Table 5)  Display of C5-H5Á Á ÁO1 C(6) chains (dashed lines) running parallel to the c axis in (III). Table 4 Comparison of various parameters ( ) in the crystal structures of series 1: N-(2-methylphenylsulfonyl)-para-substituted-arylamides.

Figure 11
Display of various weak interactions (dashed lines) in the crystal structure of (III).

Synthesis and crystallization
Compounds (I)-(III) were prepared by refluxing a mixture of 4-fluorobenzoic acid, the corresponding substituted benzenesulfonamides and phosphorousoxychloride for 3 h on a water bath. The resultant mixtures were cooled and poured into icecold water. The solids obtained were filtered, washed thoroughly with water and then dissolved in sodium bicarbonate solutions. The compounds were later re-precipitated by acidifying the filtered solutions with dilute HCl. They were filtered, 580 Suchetan et al. C 14 H 12 FNO 3 S, C 13 H 9 ClFNO 3 S and C 13 H 9 ClFNO 3 SÁH 2 O Acta Cryst. (2016). E72, 575-582 research communications Table 5 Comparison of various parameters ( ) in the crystal structures of series 2: N-(2-chlorophenylsulfonyl)-para-substituted-arylamides.

Refinement
Crystal data, data collection and structure refinement details are summarized in Table 7. The H atoms of the NH groups in (I)-(III) were located in difference Fourier maps and freely refined. The H atoms of the water molecule in (III) were located in a difference Fourier map and were refined with the bond length restraint O-H = 0.83 (3) Å . The other H atoms were positioned with idealized geometry using a riding model: C-H = 0.93-0.96 Å , with U iso = 1.5U eq (C-methyl) and 1.2U eq (C) for other H atoms. In the final cycles of refinement, reflections (0 1 1), (0 0 2) and (7 0 20) in (I), (0 0 2) in (II) and (2 0 0) in (III) were omitted due to large differences in F 2 obs and F 2 calc .

Hydrogen-bond geometry (Å, º)
Cg is the centroid of the fluorobenzene ring of molecule B of (I). Symmetry codes: (i) −x, −y+2, −z; (ii) −x, y−1/2, −z+1/2; (iii) x−1, y, z. where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max < 0.001 Δρ max = 0.37 e Å −3 Δρ min = −0.50 e Å −3 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. where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max = 0.001 Δρ max = 0.34 e Å −3 Δρ min = −0.35 e Å −3 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.

sup-12
Acta Cryst. (2016). E72, 575-582 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.