N-[4-(4-Chlorobenzenesulfonamido)phenylsulfonyl]acetamide

In the title compound, C14H13ClN2O5S2, the dihedral angles between the central benzene ring and the pendant chlorobenzene ring and the N-acetyl group are 82.35 (5) and 79.71 (6)°, respectively, and the overall conformation of the molecule approximates to a U shape. Both the C—S—N—C conformations are gauche, but with opposite senses [torsion angles = −59.29 (15) and 63.68 (16)°]. An intramolecular C—H⋯O interaction generates an S(6) ring. In the crystal, inversion dimers linked by pairs of N—H⋯O hydrogen bonds generate R 2 2(20) loops. A second N—H⋯O hydrogen bond links the dimers into (101) layers.

In the title compound, C 14 H 13 ClN 2 O 5 S 2 , the dihedral angles between the central benzene ring and the pendant chlorobenzene ring and the N-acetyl group are 82.35 (5) and 79.71 (6) , respectively, and the overall conformation of the molecule approximates to a U shape. Both the C-S-N-C conformations are gauche, but with opposite senses [torsion angles = À59.29 (15) and 63.68 (16) ]. An intramolecular C-HÁ Á ÁO interaction generates an S(6) ring. In the crystal, inversion dimers linked by pairs of N-HÁ Á ÁO hydrogen bonds generate R 2 2 (20) loops. A second N-HÁ Á ÁO hydrogen bond links the dimers into (101) layers.

Comment
As part of our ongoing structural studies of sulfonamides (Ashfaq et al., 2009(Ashfaq et al., , 2010, the synthesis and structure of the title compound, (I), (Fig. 1), are now described.

Experimental
Sodium sulfacetamide (0.236 g, 1.0 mmol) was dissolved in 30 ml distllled water in a 100-ml round bottom flask and the pH was adjusted to 8.0 using Na 2 CO 3 solution (3%). 4-Chlorobenzenesulfonyl chloride (0.422 g, 2.0 mmol) was added and the mixture was stirred at 50 °C for about 5 h. The pH was adjusted to 3.0 using HCl (3 N) and the resulting white precipitate was filtered, washed and dried. Colourless blocks of (I) were recrystallized from methanol solution at room temperature. This compound has been deposited to CSD with CCDC No. 859957.

Refinement
The N-bound H atoms were located in a difference map and their positions and U iso values were freely refined. The Cbound hydrogen atoms were placed in calculated positions (C-H = 0.93-0.96 Å) and refined as riding atoms with U iso (H) = 1.2U eq (C) or 1.5U eq (methyl C).  The molecular structure of (I) showing 50% displacement ellipsoids.

Figure 2
An inversion dimer in the crystal of (I), which generates an R 2 2 (20) loop. Symmetry code: (i) 1-x, -y, 1-z. 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 > σ(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.