3-Fluoroanilinium 4-methylbenzenesulfonate

In the crystal structure of the title salt, C6H7FN+·C7H7O3S−, the components are linked into chains along [010] via N—H⋯O hydrogen bonds. Further stabilization is is provided by weak π–π stacking interactions, with a centroid–centroid distance of 3.7156 (12) Å.

ASP and HSY thank the UoM for research facilities. JPJ acknowledges the NSF-MRI program (grant No. CHE1039027) for funds to purchase the X-ray diffractometer.
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: LH5330).

Comment
The importance of molecular salts as solid forms in pharmaceutical formulations is well known (Stahl & Wermuth, 2002).
In the crystal structure of the title salt, C 6 H 7 FN + , C 7 H 7 O 3 S -, ( Fig. 1) N-H···O hydrogen bonds link the components into one-dimensional chains along [010] (Fig. 2). Further stabilization is is provided by weak π-π stacking interactions with a centroid to centroid distance of 3.7156 (12)Å.
Experimental 4-methylbenzenesulfonic acid monohydrate (1 g, 5.25 mmol) was added to a stirred solution of 3-fluoroaniline (0.58 g, 5.25 mmol ) in methanol (10 mL). Resulting mixture was stirred at 323 K for 10 minutes and cooled to room temperature to obtain the title compound (I), Fig. 1. The single crystal was grown from methanol by slow evaporation method (m.p.: 533 K).

Refinement
H1NA, H1NB and H1NC were intially located in a difference Fourier map. These and all of the remaining H atoms were placed in their calculated positions and then refined using the riding model with Atom-H lengths of 0.91Å (NH), 0.95Å (CH) or 0.98Å (CH 3 ). Isotropic displacement parameters for these atoms were set to 1.20 (CH, NH) or 1.50 (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.