4-(N-Propan-2-ylcarbamoyl)pyridinium perchlorate

In the title compound, C9H13N2O+·ClO4 −, the dihedral angle between the planes of the amide group and the pyridinium fragment is 34.11 (14)°. In the crystal, the cations are connected by N—H⋯O hydrogen bonds between the amide groups into chains extended along the a axis. Hydrogen bonds between the pyridinium N—H group and the perchlorate anions organize the chains into a two-dimensional network.

In the title compound, C 9 H 13 N 2 O + ÁClO 4 À , the dihedral angle between the planes of the amide group and the pyridinium fragment is 34.11 (14) . In the crystal, the cations are connected by N-HÁ Á ÁO hydrogen bonds between the amide groups into chains extended along the a axis. Hydrogen bonds between the pyridinium N-H group and the perchlorate anions organize the chains into a two-dimensional network.
Hydrogen bonds N-H···O and C-H···O make great contribution to the stability of the crystal structure (Table 1). The cations are connected by N-H···O hydrogen bonds between the amide groups into chains extended along the a axis. Hydrogen bonds between pyridinium N-H group and the perchlorate anions organize the chains into two-dimensional polymeric structure (Fig 2).
Experimental 4-(Propan-2-ylcarbamoyl) pyridine (0.492 g, 3 mmol) (Zhang et al., 2009), and HClO 4 (0.42 g, 70%) were dissolved in 15 ml of ethanol. Single crystals of the title compound suitable for X-ray analysis were obtained on slow evaporation of the solvent over a period of 7 days.
The dielectric constant of title compound as a function of temperature indicates that the permittivity is basically temperature-independent (ε=C/ (T-T 0 )), suggesting that this compound should not be a real ferroelectric and that no distinct phase transitions occur within the measured temperature range. Similarly, below the melting point (408K) of the compound, the dielectric constant as a function of temperature also goes smoothly, and no dielectric anomaly is observed.

Refinement
The C-bound H atoms were positioned geometrically, with C-H = 0.93-0.98 Å and refined as riding on their parent atoms with U iso (H) = 1.2U eq (C) or 1.5U eq (methyl). Atoms H2 and H1B were positioned geometrically and allowed to ride on N1, with N-H = 0.86 Å and U iso (H) = 1.2U eq (N).

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.