4-[(Adamantan-1-yl)carbamoyl]pyridinium chloride

In the title salt, C16H21N2O+·Cl−, the amide group makes a dihedral angle of 24.98 (2)° with respect to the pyridinium ring. In the crystal, both the amide and pyridinium N atoms are involved in N—H⋯Cl hydrogen bonding. Weak intermolecular C—H⋯Cl and C—H⋯O interactions also occur.


Ying-Chun Wang Comment
Organic amino compounds attracted more attention as phase transition dielectric materials for its application in memory storage (Fu et al., 2011a, b and c). With the purpose of obtaining phase transition crystals of amino compounds, various amines have been studied and we have elaborated a series of new materials with this organic molecules (Dai & Chen 2011;Xu, et al. 2011;Zheng 2011). In this study, we describe the crystal structure of the title compound, 4-[(adamantyl)carbamoyl]pyridinium chloride.

Experimental
Isonicotinic acid 5 g was added in thionyl chloride (50 ml), and the mixture reacted at 353 K for 5 h. Then the solvate was removed under reduced pressure, the isonicotinoyl chloride was obtained. The 1-aminodiamantane hydrochloride (10 mmol) and triethylamine 2.02 g (20 mmol) dissolved in chloroform (40 ml) at 273 K, then the isonicotinoyl chloride 1.51 g (10 mmol) was added. Then the reactant mixture was stired for 7 h at room temperature and some flaxen solid appeared. After filtering the mixture, the solid was dissolved in water and was neutralized with sodium carbonate, The mixed solution was extracted by dichloromethane. The N-(1-adamantyl)isonicotinamide was obtained when the dichloromethane was evaporated under reduced pressure. A mixture of N(1-adamantyl)isonicotinamide 2.56 g (10 mmol), HCl (2.0 mL, 6 mol/L), and 20 mL ethanol were added into a 50ml flask and refluxed for 5 hours, then cooled and filtrated.
The solution was evaporated slowly in the air. Colorless block crystals suitable for X-ray analysis were obtained after one week.

Refinement
All H atoms attached to C atoms were fixed geometrically and treated as riding with C-H = 0.95 Å (aromatic), C-H = 0.99 Å (methylene) and C-H = 1.00 Å (methine) with U iso (H) = 1.2U eq (C). H atoms bonded to N atoms were located in difference Fourier maps and restrained with the H-N = 0.86 (2)Å. In the last stage of refinement they were treated as riding on the N atoms with U iso (H) = 1.2U eq (N).

Figure 1
Molecular view of the title compound with the atomic numbering scheme. Displacement ellipsoids are 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.