2-Amino-5-bromopyridinium trifluoroacetate

In the title compound, C5H6BrN2 +·C2F3O2 −, the F atoms of the anion are disordered over two sets of sites, with occupancies of 0.59 (2):0.41 (2). In the crystal structure, the anions and cations are linked into a two-dimensional network parallel to (100) by N—H⋯O and C—H⋯O hydrogen bonds. Within this network, the N—H⋯O hydrogen bonds generate R 2 2(8) ring motifs.

In the title compound, C 5 H 6 BrN 2 + ÁC 2 F 3 O 2 À , the F atoms of the anion are disordered over two sets of sites, with occupancies of 0.59 (2):0.41 (2). In the crystal structure, the anions and cations are linked into a two-dimensional network parallel to (100) by N-HÁ Á ÁO and C-HÁ Á ÁO hydrogen bonds. Within this network, the N-HÁ Á ÁO hydrogen bonds generate R 2 2 (8) ring motifs.
In the crystal packing (Fig. 2), the cations and anions are linked via N-H···O hydrogen bonds to form R 2 2 (8) ring motifs (Bernstein et al., 1995). The ionic units are linked into a two-dimensional network parallel to the (100) by N-H···O and C-H···O hydrogen bonds (Table 1).

Experimental
To a hot methanol solution (20 ml) of 2-amino-5-bromopyridine (44 mg, Aldrich) was added a few drops of trifluoroacetic acid. The solution was warmed over a water bath for a few minutes. The resulting solution was allowed to cool slowly to room temperature. Crystals of the title compound appeared after a few days.

Refinement
Atoms H1N1, H1N2 and H2N2 were located in a difference Fourier map and refined; the N-H distances of the NH 2 group were restrained to be equal. The remaining H atoms were positioned geometrically [C-H = 0.93 Å] and were refined using a riding model, with U iso (H) = 1.2U eq (C). The F atoms of the anion are disordered over two positions with occupancies of 0.59 (2):0.41 (2). The C-F distances were restrained to be equal and the U ij components of F atoms were restrained to an approximate isotropic behaviour.
supplementary materials sup-2 Figures   Fig. 1. The asymmetric unit of the title compound. Displacement ellipsoids are drawn at the 30% probability level. Both disorder components are shown.