2-Amino-5-bromopyridin-1-ium (2-amino-5-bromopyridine-κN 1)trichloridozincate

The structure of the title salt, (C5H6BrN2)[ZnCl3(C5H5BrN2)], consists of discrete 2-amino-5-bromopyridin-1-ium cations and distorted tetrahedral (2-amino-5-bromopyridine)trichloridozincate anions. In the crystal, the complex anions and cations are linked via N—H⋯Cl hydrogen bonds into layers parallel to (101). Short Br⋯Cl contacts of 3.4239 (11) and 3.4503 (12) Å are observed, as well as π–π stacking interactions between the pyridine and pyridinium rings, with alternating centroid-to-centroid distances of 3.653 (2) and 3.845 (2) Å.

A short halogen···halogen contact of the type Br···Cl is found between the Br1 atom of the 2-amino-5-bromopyridine ligand of the complex anion and the Cl2 atom of an adjacent complex anion [Br1···Cl2 = 3.4239 (11) Å]. Furthermore, the Br2 atom of the neighbouring 2-amino-5-bromopyridinium cation also has a short contact to this Cl2 atom with a Br2···Cl2 distance of 3.4503 (12) Å as depicted in Fig. 3.

Experimental
The title compound was synthesized by dissolving zinc chloride (480 mg, 3 mmol) in methanol (10 ml) which was added to a methanolic solution of 2-amino-5-bromopyridine (519 mg, 3 mmol). The reaction mixture was stirred in the presence of a few drops of concentrated hydrochloric acid. The final pH of the solution was adjusted to 3. After stirring for 5 h, the resulting solution was filtered off and the filtrate was left for slow evaporation of the solvent at ambient temperature.
After several days, brown crystals suitable for X-ray diffraction analysis were collected by filtration, washed several times with methanol and dried in a desiccator over silica gel.
The analytical data of the zinc(II) complex are given as follows.

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.