1,4-Bis[4-(methoxycarbonyl)benzyl]-1H-1,2,4-triazol-4-ium bromide

In the title salt, C20H20N3O4 +·Br−, the dihedral angle between the benzene rings is 8.69 (16)°, and those between the benzene rings and the triazole ring are 69.98 (18) and 72.17 (18)°. In the crystal, C—H⋯Br hydrogen bonds link the cations and anions into chains along the c axis.


Related literature
In an earlier report, we presented a N-heterocyclic benzimidazole derivative. The crystal structure consists of infinite chains connected via C-H···Br and C-H···O hydrogen bonds; it also shows π···π stacking interactions (Huang et al., 2010).
The bromide anions and cations form infinite hydrogen bonding chains along the c-axis via C-H···Br hydrogen bonds between the bromide anions and carbineen atoms of triazole ring and ethylene linkage (Fig. 2, Table 1).
The solvent was evaporated under reduced pressure. The solid residue was recrystallized in methanol, and colorless block crystals were obtained after few days, yield 1.42 g, 63.5%.
The FAB mass spectrum showed tje ions at 447.

Refinement
The C-bound H atoms were positioned geometrically and were included in the refinement in the riding-model approximation, with distances 0.98 (CH 3 ), 0.99 (CH 2 ) and 0.95 Å (aromatic and triazole); U iso (H) = xU eq (attached atom), where x = 1.5 for methyl C and 1.2 for all other C.   Crystal packing of the title compound. Dashed lines indicate hydrogen bonds. Symmetry: I = -x + 1, -y + 1, z + 1/2; II = -

Computing details
x + 1, -y + 2, z + 1/2. H atoms not involved in the hydrogen bond interactions have been omitted.

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.