Crystal structures of N-(3-fluorobenzoyl)benzenesulfonamide and N-(3-fluorobenzoyl)-4-methylbenzenesulfonamide

In the title compounds, N—H⋯O hydrogen bonds lead to dimers; the dimers are linked by weak interactions into a three-dimensional network in one case and chains in the other.


Chemical context
N-(Arylsulfonyl)arylamides have received much attention as they constitute an important class of drugs for Alzheimers disease (Hasegawa et al., 2000), antibacterial inhibitors of tRNA synthetases (Banwell et al., 2000), antagonists for angiotensin II (Chang et al., 1994) and as leukotriene D4receptors (Musser et al., 1990). Further, N-(arylsulfonyl)arylamides are known to be potent antitumour agents against a broad spectrum of human tumour xenografts (colon, lung, breast, ovary and prostate) in nude mice (Mader et al., 2005). As part of our ongoing work on the synthesis and crystal structures of this class of compound (Gowda et al., 2009a,b;Sreenivasa et al., 2014;Suchetan et al., 2010Suchetan et al., , 2012, compounds (I) and (II) were synthesized and their crystal structures were determined. ISSN 2056-9890

Structural commentary
The meta-fluoro substitution on the benzoyl ring of (I) (Fig. 1) is syn to the N-H bond in the central -C-SO 2 -N-C( O)-segment. By contrast, in (II) (Fig. 2), the conformation of the N-H bond is anti with respect to the metafluoro substitution on the benzoyl ring. The dihedral angle between the benzene rings is 82.73 (10) in (I), while, in (II) the value is slightly less [72.60 (12) ]. Further, in (I), the dihedral angle between the benzoic acid ring and the central C8-C7(O3)-N1-S1 segment is 16.54 (10) , while that between the sulfonamide ring and the C7(O3)-N1-S1-C1 segment is 81.87 (12) . The corresponding values in (II) are slightly less than those observed in (I), being 12.12 (12) and 57.58 (13) , respectively.

Supramolecular features
The crystal structure of (I) features strong N1-H1Á Á ÁO1 hydrogen bonds (Table 1) that connect the molecules into R 2 2 (8) dimers (Fig. 3). These dimers are further interconnected by C9-H9Á Á ÁO1 interactions, forming R 2 2 (14) ring motifs. C6-H6Á Á ÁO3 interactions connect these dimers into C7 chains, forming columns propagating along the b-axis direction (Fig. 3). In addition, C4-H4Á Á Á aryl ( system of the fluorobenzoyl ring) interactions link the molecules into chains along the c axis. These chains are interconnected via C2-H2Á Á Á aryl ( system of the sulfonylbenzene ring) and C11-H11Á Á Á aryl ( system of the sulfonylbenzene ring) interactions, forming a three-dimensional grid-like structure (Fig. 4). The crystal structure also features -( system of the fluorobenzoyl ring) stacking interactions. It is notable that the N-HÁ Á ÁO hydrogen bonds present in the crystal structure of (I) has no structure-directing properties (leading only to dimers), while one of the C-HÁ Á ÁO and the three C-H.. aryl interactions have structure-directing characteristics.
Similar to that observed in the crystal structure of (I), in (II) strong N1-H1Á Á ÁO1 hydrogen bonds ( A view of the molecular structure of (I), with displacement ellipsoids drawn at the 50% probability level.

Figure 2
A view of the molecular structure of (II), with displacement ellipsoids drawn at the 50% probability level. Table 1 Hydrogen-bond geometry (Å , ) for (I).

Figure 3
Crystal packing of (I), displaying N-HÁ Á ÁO hydrogen bonds and C-HÁ Á ÁO interactions, which result in columns along the b axis.
these dimers are interconnected into R 2 2 (14) ring motifs via C13-H13Á Á ÁO1 interactions, as observed in (I). Adjacent dimers are interconnected via C5-H5Á Á ÁO3 interactions into R 2 2 (16) rings, thus forming ribbons along the diagonal of the ac plane (Fig. 5). The overall supramolecular architecture displayed in (II) is one-dimensional, in contrast to the threedimensional architecture displayed in (I).

Database survey
The crystal structures of five related N-(arylsulfonyl)arylamides, namely N-(benzoyl)benzenesulfonamide (III), N-(3-chlorobenzoyl)benzenesulfonamide (IV), N-(3-methylbenzoyl)benzenesulfonamide (V), N-(benzoyl)-4-methylbenzenesulfonamide (VI) and N-(3-methylbenzoyl)-4-methylbenzenesulfonamide (VII) have previously been reported. A comparison of the dihedral angle between the two benzene rings in these closely related structures indicates that introducing a methyl substituent into the para position of the benzenesulfonyl ring lowers the dihedral angle with compound (VII) being an exception. The dihedral angle values are 80.3 (1) in (III) (Gowda et al., 2009a), 87.5 (1) in (IV) (Gowda et al., 2009b), 83.3 (2), 84.4 (2) and 87.6 (2) in the three molecules of (V) (Suchetan et al., 2012), 79.4 (1) in (VI) (Suchetan et al., 2010) and 89.6 (2) in (VII) (Sreenivasa et al., 2014). This effect is the same as that observed in the present two structures (I) and (II). Furthermore, in (I)-(VII) the conformation of the N-H bond in the central segment is anti to the meta substituent on the benzoyl ring in the presence of a methyl substituent either on the benzoyl ring or the benzenesulfonyl ring. Otherwise, the conformation is syn as observed in (I) and (IV). A comparison of the crystal structures of (I) and (II) with those previously reported shows that fluoro substitution on the benzoyl ring appears to have a significant effect on the supramolecular architecture, and also on the type and nature of the intermolecular interactions displayed. For instance, in all the reported structures except (VII), the molecules are linked into one-dimensional infinite C(4) chains via strong structure-directing N-HÁ Á ÁO hydrogen bonds. The structures do not feature any other type of interactions. However, in (I) and (II), the N-HÁ Á ÁO hydrogen bonds lead to dimers and, in addition, both of them feature other structure-directing interactions of the type C-HÁ Á ÁO or C-HÁ Á Á aryl . Furthermore, introducing the methyl substituent into the benzenesulfonyl ring of (I) to form (III) reduces the three-dimensional grid-like architecture into a onedimensional ribbon architecture. However, in (III)-(VII), the introduction of a methyl substituent into the benzenesulfonyl ring results in no change to the supramolecular architecture.

Figure 5
One-dimensional ribbons formed in the crystal structure of (II) via N-HÁ Á ÁO dimeric pairs and various C-HÁ Á ÁO dimeric pairs. nate solutions. The compounds were later reprecipitated by acidifying the filtered solutions with dilute HCl. They were filtered, dried and recrystallized; m.p = 442-444 K for (I) and 422-423 K for (II). Prism-like, colourless single crystals of (I) and (II) were obtained by slow evaporation of the respective solutions of the compounds in methanol (with a few drops of water).

Refinement
Crystal data, data collection and structure refinement details are summarized in Table 3. The H atoms of the NH groups in (I) and (II) were located in a difference map and later refined freely. The other H atoms were positioned with idealized geometry using a riding model with C-H = 0.93-0.96 Å , and with U iso = 1.2 or 1.5U eq (parent atom). To improve considerably the values of R1, wR2 and GOOF, reflections with very bad agreement (À20 0 0), (À20 0 10) and (À19 1 15) in (I) and (0 6 0) in (II) were omitted from the final refinements.

Computing details
For both compounds, data collection: APEX2 (Bruker, 2009); cell refinement: SAINT-Plus (Bruker, 2009); data reduction: SAINT-Plus (Bruker, 2009); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: Mercury (Macrae et al., 2008); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008). 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.