4-[3,5-Bis(ethoxycarbonyl)-2,6-dimethyl-4-pyridyl]pyridinium nitrate

In the title molecular salt, C18H21N2O4 +·NO3 −, the dihedral angle between the two pyridine rings is 61.24 (8)°. In the crystal, the cation and anion are linked by intermolecular N—H⋯O hydrogen bonds.

In the title molecular salt, C 18 H 21 N 2 O 4 + ÁNO 3 À , the dihedral angle between the two pyridine rings is 61.24 (8) . In the crystal, the cation and anion are linked by intermolecular N-HÁ Á ÁO hydrogen bonds.
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: HB5413).

4-[3,5-Bis
In recent years, the design and construction of metal-organic frameworks through the coordination of metal ions with multifunctional organic ligands have received extensive attention due to their impressive structural diversities in architectures and their potential applications as functional materials (Zhang et al., 2003). Whereas, it is more important to design the novel organic ligand. Here, we describe the recystallization and structural characterization of the title compound.
The molecular structure is shown in Fig 1. The dihedral angle between the two pyridine rings is 61.24 (8) °. N-H···O and N-H···N hydrogen bonding between the cations and anions leads to a consolidation of the structure ( Fig. 2; Table 1).

Refinement
The absolute structure of (I) is indeterminate based on the present model. All hydrogen atoms bound to aromatic carbon atoms were refined in calculated positions using a riding model with a C-H distance of 0.93 Å and U iso = 1.2U eq (C).
Hydrogen atoms attached to aromatic N atoms were refined with a N-H distance of 0.86 Å and U iso = 1.2U eq (N). Fig. 1. The moleular structure of (I) with displacement ellipsoids drawn at the 30% probability level; H atoms are given as spheres of arbitrary radius.

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 > σ(F 2 ) is used only for calculating R-supplementary materials sup-3 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.