2-Cyanoquinolin-1-ium nitrate

A proton is transferred from the nitric acid to the N atom of 2-cyanoquinoline during crystallization, resulting in the formation of the title salt, C10H7N2 +·NO3 −. The quinolinium ring system is approximately planar, with a maximum deviation of 0.013 (3) Å. In the crystal, a very asymmetric bifurcated N—H⋯(O,O) hydrogen bond to two O atoms of an adjacent nitrate anion occurs, generating an R 2 1(4) ring motif. C—H⋯O hydrogen bonds link the ions into sheets stacking along the a axis.

A proton is transferred from the nitric acid to the N atom of 2cyanoquinoline during crystallization, resulting in the formation of the title salt, C 10 H 7 N 2 + ÁNO 3 À . The quinolinium ring system is approximately planar, with a maximum deviation of 0.013 (3) Å . In the crystal, a very asymmetric bifurcated N-HÁ Á Á(O,O) hydrogen bond to two O atoms of an adjacent nitrate anion occurs, generating an R 2 1 (4) ring motif. C-HÁ Á ÁO hydrogen bonds link the ions into sheets stacking along the a axis.

Comment
Recently, hydrogen-bonding patterns involving quinoline and its derivatives with organic acid have been investigated (Loh at al., 2010a,b;Loh et al., 2010). Syntheses of the quinoline derivatives were discussed earlier (Sasaki et al., 1998;Reux et al., 2009). Quinolines and their derivatives are very important compounds because of their wide occurrence in natural products (Morimoto et al., 1991;Michael, 1997) and biologically active compounds (Markees et al., 1970;Campbell et al., 1988). Heterocyclic molecules containing cyano group are useful as drug intermediates. Herein we report the synthesis of 2-cyanoquinolin-1-ium nitrate.

Experimental
A few drops of nitric acid were added to a hot methanol solution (20 ml) of quinoline-2-carbonitrile (39 mg, Aldrich) which had been warmed over a magnetic stirrer hotplate for a few minutes. The resulting solution was allowed to cool slowly to room temperature. Colourless plates of (I) appeared after a few days.

Refinement
All H atoms were located from a difference Fourier map. H1N1 was fixed at its found position with bond length of N-H being 0.9481 Å. The remaining H atoms were refined freely with the bond lengths of C-H being 0.943 (17) to 0.998 (17) Å.

Special details
Experimental. The crystal was placed in the cold stream of an Oxford Cryosystems Cobra open-flow nitrogen cryostat (Cosier & Glazer, 1986) operating at 100.0 (1) K. 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.