Quinoline-2-carbonitrile–fumaric acid (1/0.5)

The asymmetric unit of the title compound, C10H6N2·0.5C4H4O4, consists of one quinoline-2-carbonitrile molecule and a half-molecule of fumaric acid, which lies on an inversion center. The quinoline-2-carbonitrile molecule is almost planar, with an r.m.s. deviation of 0.008 (1) Å. The acid and base are linked together via pairs of intermolecular C—H⋯O and O—H⋯N hydrogen bonds, forming R 2 2(8) ring motifs. In the crystal, the carbonitrile molecules are further linked by intermolecular C—H⋯N hydrogen bonds, generating R 2 2(10) ring motifs, resulting in zigzag chains running along the c axis.

The asymmetric unit of the title compound, C 10 H 6 N 2 Á-0.5C 4 H 4 O 4 , consists of one quinoline-2-carbonitrile molecule and a half-molecule of fumaric acid, which lies on an inversion center. The quinoline-2-carbonitrile molecule is almost planar, with an r.m.s. deviation of 0.008 (1) Å . The acid and base are linked together via pairs of intermolecular C-HÁ Á ÁO and O-HÁ Á ÁN hydrogen bonds, forming R 2 2 (8) ring motifs. In the crystal, the carbonitrile molecules are further linked by intermolecular C-HÁ Á ÁN hydrogen bonds, generating R 2 2 (10) ring motifs, resulting in zigzag chains running along the c axis.

Comment
Heterocyclic molecules containing the cyano group are useful as drug intermediates. Syntheses of quinoline derivatives have been discussed earlier (Sasaki et al., 1998;Reux et al., 2009). In continuation of our previous work, we have synthesized a number of quinoline compounds to investigate the hydrogen bonding patterns in these compounds Loh, Quah et al., 2010;Quah et al., 2010). Here we report the synthesis of quinoline-2-carbonitrile fumaric acid.

Experimental
A hot methanol solution (20 ml) of quinoline-2-carbonitrile (39 mg, Aldrich) and fumaric acid (29 mg, Aldrich) were mixed and warmed over a magnetic stirrer hotplate for a few minutes. The resulting solution was allowed to cool slowly to room temperature. Colourless crystals suitable for X-ray diffraction appeared after a few days.

Refinement
H1O2 was located from a difference Fourier map and refined freely (O-H = 0.92 (2) Å). The remaining H atoms were positioned geometrically with C-H = 0.93 Å and were refined using a riding model, with U iso (H) = 1.2 U eq (C). Fig. 1. The molecular structure of the title compound showing 50% probability displacement ellipsoids for non-H atoms and the atom-numbering scheme. Atoms with suffix A were generated by the symmetry code -x, -y + 1, -z + 1. Hydrogen atoms are shown as spheres of arbitrary radius.

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.