(±)-5-Ethyl-2-(4-isopropyl-4-methyl-5-oxo-4,5-dihydro-1H-imidazol-2-yl)nicotinic acid

In the title compound, C15H19N3O3, owing to an intramolecular O—H⋯N hydrogen bond, the pyridine and imidazole rings are nearly coplanar and are twisted from each other by a dihedral angle of only 0.92 (9)°. The molecules are linked through intermolecular N—H⋯O hydrogen bonding, forming an infinite chain parallel to the b axis.


Comment
The nicotinic acid and the imidazole group have found a wide range of applications in coordination chemistry as ligands, in medicinal chemistry and materials science (Liu et al. 2005;Zhao et al. 2007;He et al. 2005;Boovanahalli et al. 2007;Song et al. 2006). We report here the crystal structure of the title compound, C 15 H 19 N 3 O 3 .
Owing to an intramolecular O1-H1···N2 hydrogen, the pyridine and the imidazole rings are nearly planar, they are only twisted to each other by a dihedral angle of 0.91 (9) . In the imidazole ring, the C6=N2 bond distance of 1.282 (4) Å conforms to the value for a double bond, while the C11-N2 bond length of 1.472 (4) Å conforms to the value for a single bond. To the carboxyl group, the C9=O2 bond distance of 1.212 (4) Å conforms to the value for a double bond, while the C9-O1 bond length of 1.298 (4) Å conforms to the value for a single bond.
The molecules are linked through intermolecular N3-H3···O2 hydrogen bond forming an infinite chain parallel to the b axis. (Table 1 and Fig. 2).

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 Rfactors(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.