2,5-Dichloroanilinium 4-chlorobenzenesulfonate

In the crystal of the title compound, C6H6Cl2N+·C6H4ClO3S−, the 2,5-dichloroanilinium cations and 4-chlorobenzenesulfonate anions are located on a crystallographic mirror plane and are connected by N—H⋯O hydrogen bonds. In the crystal, the connectivity of the hydrogen bonds leads to double chains propagating in [010].

KS thanks the University Grants Commission, Government of India, New Delhi for the award of a research fellowship under its faculty improvement program.
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: BT5496).

Comment
The amine and sulfonate moieties are important constituents of many important compounds. As a part of studying the substituent effects on the structures of this class of compounds (Gowda et al., 2004a(Gowda et al., , 2004b(Gowda et al., , 2007, in the present work, the crystal structure of 2,5-dichloroanilinium, 4-chlorobenzenesulfonate (I) has been determined (Fig. 1). The title compound showed interesting H-bonding in its crystal structure (Fig. 2). It forms the structure through N-H···O(S) hydrogen bonding. Three H-atoms of the positively charged NH 3 group have three O atoms of the negatively charged sulfonate anion as acceptors, with each oxygen forming H-bonding with three H-atoms, one each from three positively charged NH 3 groups.

Experimental
The solution of chlorobenzene (10 ml) in chloroform (40 ml) was treated dropwise with chlorosulfonic acid (25 ml) at 0° C. After the initial evolution of hydrogen chloride subsided, the reaction mixture was brought to room temperature and poured into crushed ice in a beaker. The chloroform layer was separated, washed with cold water and allowed to evaporate slowly. The residual 4-chlorobenzenesulfonylchloride was treated with 2,5-dichloroaniline in the stoichiometric ratio and boiled for ten minutes. The reaction mixture was then cooled to room temperature and added to ice cold water (100 ml). The resultant title compound (I) was filtered under suction and washed thoroughly with cold water. It was then recrystallized to constant melting point from dilute ethanol.
Prism like colorless single crystals used in X-ray diffraction studies were grown in ethanolic solution by slow evaporation at room temperature.

Refinement
The N bounded H atoms were located in a difference map and later restrained to the distance N-H = 0.86 (2) Å. The other H atoms were positioned with idealized geometry using a riding model with C-H = 0.93 Å. All H atoms were refined with isotropic displacement parameters set to 1.2 times of the U eq of the parent atom.  as those based on F, and R-factors based on ALL data will be even larger.