2-Aminoanilinium benzoate

In the crystal of the title molecular salt, C6H9N2 +·C7H5O2 −, the cations and anions are linked by N—H⋯O hydrogen bonds, buiding an R 2 2(9) ring. Futher N—H⋯O hydrogen bonds generate chains, which develop parallel to the a axis through the formation of R 4 3(10) rings.,


Comment
The amino derivatives have found wide range of applications in material science, such as magnetic, fluorescent and dielectric behaviors. And there has been an increased interest in the preparation of amino coordination compound (Aminabhavi et al., 1986;Dai & Fu 2008a;Dai & Fu 2008b;Fu, et al. 2009). As an extension on the structural characterization, we report here the crystal structure of the title compound 2-aminoanilinium benzoate.
The asymmetrical unit of the title compound consists of one benzene-1,2-diamine cation and one benzoic acid anion linked by N-H···O hydrogen bonds buiding a R 2 2 (9) ring (Etter, 1990, Bernstein et al., 1995 (Fig.1; Table 1). As expected The carboxyl acid group has protonated one of the amine N atom.

Experimental
A mixture of benzene-1,2-diamine (0.1 mmol) and benzoic acid (0.1 mmol) was dissolved in ethanol (20 ml). The solution was allowed to evaporate to obtain colourless block-shaped crystals of the title compound.

Refinement
All H atoms attached to C atoms and N(NH 3 ) were fixed geometrically and treated as riding with C-H = 0.93 Å and N-H = 0.85Å with U iso (H) = 1.2U eq (C) or U iso (H) = 1.5U eq (N) . H atoms bonded to N(NH 2 ) atom were located in difference Fourier maps and their coordinates were refined using restraints (N-H=1.00 (1)Å; H···H = 1.80 (2) Å) with U iso (H) = 1.5U eq (N).
In the last cycle of refinement they were treated as riding on the N.
In the absence of significant anomalous scattering, the absolute configuration could not be reliably determined and then the Friedel pairs were merged and any references to the Flack parameter were removed.

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.