5-(Pyridinium-4-yl)-1H-1,2,3,4-tetrazol-1-ide

In the title zwitterionic molecule, C6H5N5, the tetrazole and pyridine rings are nearly coplanar, making a dihedral angle of 2.08 (1)°. In the crystal, molecules are connected by classical N—H⋯N and weak C—H⋯N hydrogen bonds.

In the title zwitterionic molecule, C 6 H 5 N 5 , the tetrazole and pyridine rings are nearly coplanar, making a dihedral angle of 2.08 (1) . In the crystal, molecules are connected by classical N-HÁ Á ÁN and weak C-HÁ Á ÁN hydrogen bonds.

Comment
Tetrazole compounds attracted more attention as phase transition dielectric materials for its application in micro-electronics, memory storage. With the purpose of obtaining phase transition crystals of tetrazole compound, a series of new materials have been elaborated with this organic molecule (Zhao et al., 2008;Fu et al., 2007;. We report here the crystal structure of the title compound, 5-(pyridinium-4-yl)tetrazol-1-ide.
The dielectric constant of title compound as a function of temperature indicates that the permittivity is basically temperature-independent, suggesting that this compound should be not a real ferroelectrics or there may be no distinct phase transition occurred within the measured temperature range. Similarly, below the melting point (413K) of the compound, the dielectric constant as a function of temperature also goes smoothly, and there is no dielectric anomaly observed (dielectric constant equaling to 6.1 to 7.9).
In the title compound ( Fig.1), the pyridine N atom is protonated, thus indicating a positive charge in the pyridine N atom. And the tetrazole ring was showing a negative charge to make the charge balance. The tetrazole and pyridine rings are twisted from each other by a dihedral angle of 2.08 (1)°. The geometric parameters of the tetrazole rings are comparable to those in related molecules (Fu et al., 2009).
In the crystal structure the molecules are connected by classic N-H···N and weak C-H···N hydrogen bonds (Table 1).
Refinement H atoms attached to N atoms were located in a difference Fourier map, and refined in riding mode with N-H = 0.86 Å and U iso (H) = 1.2U eq (N). Other H atoms were fixed geometrically and treated as riding with C-H = 0.93 Å and U iso (H) = 1.2U eq (C). As no significant anomalous scattering, Friedel pairs were merged. Fig. 1. A view of the title compound with the atomic numbering scheme. Displacement ellipsoids were drawn at the 30% 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 > 2sigma(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.