N,N′-(Propane-1,3-diyl)bis(p-toluenesulfonamide)

The complete molecule of the title compound, C17H22N2O4S2, is generated by crystallographic twofold symmetry, with one C atom lying on the rotation axis. The dihedral angle between the benzene rings is 44.04 (7)° and the conformation of the central N—C—C—C group is gauche. In the crystal, molecules are linked by N—H⋯O hydrogen bonds, generating corrugated (010) sheets, and weak C—H⋯O interactions consolidate the packing.

The complete molecule of the title compound, C 17 H 22 N 2 O 4 S 2 , is generated by crystallographic twofold symmetry, with one C atom lying on the rotation axis. The dihedral angle between the benzene rings is 44.04 (7) and the conformation of the central N-C-C-C group is gauche. In the crystal, molecules are linked by N-HÁ Á ÁO hydrogen bonds, generating corrugated (010) sheets, and weak C-HÁ Á ÁO interactions consolidate the packing.
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: OM2455).

Comment
As part of our ongoing structural studies of sulfonamides, the synthesis and structure of the title compound, (I), are now described.
The complete molecule of (I) is generated by crystallographic twofold symmetry ( Fig. 1) with atom C9 lying on the rotation axis. The diehdral angle between the benzene rings is 44.04 (7)°. The conformation of the atoms of the central (14)°; (i) = 1-x, 1-y, z] whereas the torsion angle for S1-N1-C8-C9 of -163.87 (15)° indicates a near anti conformation for these atoms. The bond-angle sum for N1 of 341.7° seems to indicate an intermediate valence state between sp 2 and sp 3 hybridization (expected bond angle sums = 328.5 and 360°, respectively).
In the crystal, the molecules are linked by N-H···O hydrogen bonds (Table 1), to generate corrugated (010) sheets ( Fig.   2). A weak C-H···O interaction may help to consolidate the packing. There is no aromatic π-π stacking in the crystal of (I).
The structure of the related compound N,N'-ethylenebis(p-toluenesulfonamide), (II), has been reported (Gajadhar- Plummer et al., 2001), in which an ethlyene bridge links the p-toluenesulfonamide units compared to a propylene bridge in (I).
The complete molcule of (II) is generated by crystallographic inversion symmetry, thus the central N-C-C-N bridge is constrained to have a perfect anti conformation. The S-N-C-C torsion angle of -98.0 (2)° in (II) is also quite different to the equivalent torsion angle in (I).

Experimental
A mixture of 1,3-diaminopropane (0.0067 mol, 0.561 ml) and p-toluenesulfonyl chloride (0.0135 mol, 2.55 g) was stirred in 20 ml distilled water while maintaining the pH of the solution at about 9.0 with sodium carbonate solution (3%). The progress of the reaction was monitored by TLC: on completion, the white precipitate formed was filtered, washed with distilled water and dried. Colourless blocks of (I) were recrystallized from methanol.

Refinement
The N-bound H atom was located in a difference map and its position was freely refined with U iso (H) = 1.2U eq (N). The C-bound hydrogen atoms were placed in calculated positions (C-H = 0.97-0.98 Å) and refined as riding atoms with U iso (H) = 1.2U eq (C) or 1.5U eq (methyl C). The methyl group was allowed to rotate, but not to tip, to best fit the electron density.