N,N′-Bis(2-chlorophenylsulfonyl)suberamide

In the crystal of the title compound, C20H22Cl2N2O6S2, the asymmetric unit comprises half of a molecule, the remaining portion is generated via an inversion centre. The conformation of the N—H and C=O bonds in the SO2–NH–C(O)–C segment is anti. The molecule is bent at the S atom with the C–SO2–NH–C(O) torsion angle being 68.16 (19)°. The dihedral angle between the plane of the benzene ring and the SO2–NH–C(O)–C segment is 77.5 (1)°. Hydrogen bonds of the type N—H⋯O(C) link molecules into supramolecular chains along the b axis.

VZR thanks the University Grants Commission, Government of India, New Delhi, for the award of a research fellowship.
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: TK2727).

Comment
The amide and sulfonamide moieties are important constituents of many biologically significant compounds. As part of an investigation studying the effect of substituents on the structures of this class of compounds (Gowda et al., 2000(Gowda et al., , 2005Rodrigues et al., 2011), in the present work, the structure of N,N-bis(2-chlorophenylsulfonyl)-suberamide (I) has been determined (Fig. 1). The asymmetric unit comprises half of a molecule, the remaining portion is generated through an inversion centre, similar to that observed in N,N-bis(2-chlorophenylsulfonyl)-adipamide (II) (Rodrigues et al., 2011). The conformation of the N-H and C═O bonds in the SO 2 -NH-C(═O)-C segment is anti. The molecule is bent at the S atom with the C-SO 2 -NH-C(═O) torsion angle being 68.16 (19) °, compared to the value of -65.1 (6)° in (II). The torsion angles C2-C1-S1-N1 and C6-C1-S1-N1 are, respectively, 70.6 (2)° and -113.32 (17)°. The corresponding values in (II) are -69.5 (6) ° and 108.8 (5) °, respectively. The dihedral angle between the planes of the benzene ring and the SO 2 -NH-C(═O)-C segment in (I) is 77.5 (1) °, compared to the value of 89.6 (2) ° in (II).

Experimental
Compound (I) was prepared by refluxing a mixture of suberic acid (0.01 mol) with 2-chlorobenzenesulfonamide (0.02 mol) and POCl 3 for 1 h on a water bath. The reaction mixture was allowed to cool and diethyl ether added. The solid product obtained was filtered, washed thoroughly with ether and hot ethanol. The compound was recrystallized to a constant melting point. Colourless prisms were grown by the slow evaporation of its ethanol solution at room temperature.

Refinement
The H atom of the NH group was located in a difference map and later restrained to the distance N-H = 0.86±0.02 Å. The other H atoms were positioned with idealized geometry using a riding model with aromati-C-H distance = 0.93 Å, and methylene-C-H = 0.97 Å. All H atoms were refined with U iso (H) = 1.2U eq (N,C). Fig. 1. Molecular structure of (I), showing the atom labelling scheme and displacement ellipsoids at the 50% probability level.   (17)