3-Methylanilinium nitrate

In the title compound, C7H10N+·NO3 −, the 3-methylanilinium cations interact with the nitrate anions through strong bifurcated N+—H⋯(O,O) hydrogen bonds, forming a two-dimensional hydrogen-bonded network.


Crystal data
Data collection: SMART (Bruker, 2001); cell refinement: SAINT (Bruker, 2001); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: Mercury (Macrae et al., 2006); software used to prepare material for publication: PLATON (Spek, 2009) and WinGX (Farrugia, 1999  The molecular geometry and labelling scheme of the title compound is illustrated in Fig. 1. The asymmetric unit contains one 3-methylanilinium cation and one trigonal planar nitrate anion. A layered structure consisting of alternating organic and inorganic layers is exhibited by the title compound. The organic layers contain the hydrophobic part of the cation, while the inorganic layers comprise the ammonium groups and nitrate anions. The molecular packing of the title compound, viewed down the b-axis, is illustrated in Fig 2(a). In the organic layer pairs of cations alternate in orientation, with all the aromatic groups packing in a single row. Aromatic interactions are present between pairs of parallel cations, packing in a head-to-tail, offset π-stacking fashion, with a centroid-to-centroid distance of 3.6347 (12) Å. Neighbouring parallel cation pairs pack with aromatic planes at an angle of 57 °. The ammonium groups of pairs of parallel cations point to pairs of nitrate anions, interacting through strong, charge assisted N + -H···Ohydrogen bonds, listed in Table 1. Each ammonium group is hydrogen bonded to three different nitrate anions through three bifurcated hydrogen bonds to six different oxygen atoms, as illustrated in Fig. 2(b). In each bifurcated hydrogen bond, one of the interactions displays an N + -H···Ointeraction angle closer to 180 °, while the angle of the second interaction deviates significantly more from linearity. In addition, for each bifurcated interaction, the two N + -H···Oangles and the -O-HOangle add up to approximately 360°. Each nitrate anion accepts three bifurcated hydrogen bonds from three different ammonium groups. The oxygen atom, O3, which accepts two approximately linear hydrogen bonds, exhibits a shorter N-O bond distance compared to the other N-O bonds.
The hydrogen bonding interactions result in a two-dimensional hydrogen bonded sheet, parallel to the ab-plane, as illustrated in Fig. 2(b). Two types of hydrogen bonded rings are present in the sheet. The larger of the two can be described by the graph set notation R 3 6 (12), while the smaller ring is described by R 2 1 (4) (Bernstein et al., 1995). supplementary materials sup-2

Refinement
All H atoms were refined using a riding model (HFIX 33 for N1 and C7), with C-H distances either 0.93 or 0.96 Å and N-H distances of 0.89 Å, and U iso (H) = 1.5U eq (C) or 1.2U eq (C) or 1.2U eq (N). The highest residual peak was 0.95 Å from atom H7B.
Figures Fig. 1. The asymmetric unit of the title compound showing the atomic numbering scheme. Displacement ellipsoids are shown at the 50% probability level.

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.