4-Chloroanilinium 4-methylbenzenesulfonate

In the crystal structure of the title salt, C6H7ClN+·C7H7O3S−, the cations and anions are linked via N—H⋯O hydrogen bonds into double chains in [101]. Weak intermolecular C—H⋯π-ring interactions link these chains into layers parallel to the ac plane.

In the crystal structure of the title salt, C 6 H 7 ClN + ÁC 7 H 7 O 3 S À , the cations and anions are linked via N-HÁ Á ÁO hydrogen bonds into double chains in [101]. Weak intermolecular C-HÁ Á Á-ring interactions link these chains into layers parallel to the ac plane.

Experimental
Cg2 is the centroid of the C8-C13 ring. Comment A variety of pharmaceutical drugs are prepared as salts of benzenesulfonic acid and are known as besylates. Recently much attention has been devoted to simple molecular-ionic crystals containing organic cations and anions due to the tunability of their special structural features and their interesting physical properties (Czupinski et al., 2002;Katrusiak & Szafranski, 2006). In the title compound, the proton of the sulfonic group of sulfonic acid has been transferred to the N atom of the 4-chloroaniline molecule, leading to the formation of the molecular complex, (I).

Refinement
H1NA, H1NB and H1NC were located by a Fourier map and refined isotropically (for N1, dfix = 0.94 (2)Å; dang = 1.50 (2)Å). All of the remaining H atoms were placed in their calculated positions and then refined using the riding model with Atom-H lengths of 0.95 (CH) or 0.98Å (CH 3 ). Isotropic displacement parameters for these atoms were set to 1.18-1.21 (CH) or 1.51 (CH 3 ) times U eq of the parent atom.

Special details
Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds 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 > σ(F 2 ) is used only for calculating Rfactors(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.