N-Methyl-4-nitroanilinium chloride

The asymmetric unit of the title salt, C7H9N2O2 +·Cl−, contains two independent cations and anions. In the crystal, each N-methyl-4-nitroanilinium cation is linked to two Cl− anions via N—H⋯Cl hydrogen bonds. π–π stacking is observed between the benzene rings of adjacent cations [centroid-to-centroid distances = 3.7684 (14) and 3.7917 (7) Å].

The title compound consists of a N-(4-nitrophenyl)-methylammonium cation and a chloride anion. The hydrochloric acid deprotonated and the N-methyl-4-nitrobenzenamine accepts the proton to produce the protonated organic cation, namely N-(4-nitrophenyl)-methylammonium chloride. In the crystal structure, contains two cations and two anions. They are linked by N-H···Cl hydrogen bonds to form a three-dimensional complex network.

Experimental
The title compound was synthesized by N-methyl-4-nitrobenzenamine and concentrated hydrochloric acid in acetone at room temperature. Single crystals suitable for X-ray diffraction were obtained by evaporation of a solution of the title compound in acetone at room temperature.

Refinement
H atoms bonded to N atoms were located in a difference Fourier map and refined isotropically with bond restraint of N-H = 0.89 (2) Å. Other H atoms were positioned geometrically and treated as riding with C-H = 0.93-0.96 Å, and refined as riding with U iso (H) = 1.2-1.5U eq (C).  The molecular structure of the title compound.

Figure 2
The packing of the title compound.

Special details
Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s 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 R-factors(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.