4-Cyano-1-methylpyridinium perchlorate

The title salt, C7H7N2 +·ClO4 −, crystallizes with alternating cations and anions in wavy sheets, which are formed by a number of C—H⋯O and C—H⋯N hydrogen bonds, lying approximately parallel to (001).

The title salt, C 7 H 7 N 2 + ÁClO 4 À , crystallizes with alternating cations and anions in wavy sheets, which are formed by a number of C-HÁ Á ÁO and C-HÁ Á ÁN hydrogen bonds, lying approximately parallel to (001).

Comment
The title compound, Fig. 1, crystallizes with alternating cations and anions in wavy sheets, which are formed by a number of C-H···O and C-H···N hydrogen bonds, which are approximately parallel to (001) [see Table 1 and Fig. 2].
As with 3-cyano-1-methylpyridinium perchlorate (McCormick et al., 2014), the perchlorate ions are located near the pyridinium nitrogen atoms as the result of electrostatic attraction but the remainder of the two structures differ considerably due to the different position of the cyano group and the effect this has on the weak interionic interactions.

Experimental
4-Cyanopyridine (10.55 g) was dissolved in benzene (40 ml). Iodomethane (9.5 ml) was added to this solution slowly with stirring and the solution was refluxed for 75 minutes. Yellow solid 4-cyano-1-methylpyridinium iodide (m.p. 189-193° C) was collected by vacuum filtration. This solid (0.98 g) was then dissolved in a solution of silver perchlorate previously prepared by reacting Ag 2 O (0.47 g) with 0.5 M aqueous HClO 4 (8.0 ml). After stirring, precipitated AgI was removed by vacuum filtration and the filtrate containing 4-cyano-1-methylpyridinium perchlorate (m.p.114-119° C) was slowly evaporated to dryness to form crystals of the title compound.

Refinement
H-atoms were placed in calculated positions (C-H = 0.95 -0.98 Å) and included as riding contributions with U iso (H) = 1.5U eq (C-methyl) and = 1.2U eq (C) for other H atoms.

Figure 1
A view of the molecular structure of the title compound, with atom labelling. Displacement ellipsoids are drawn at the 50% probability level.

Figure 2
A view of the crystal packing along the b axis, with the C-H···O and C-H···N hydrogen bonds as red and blue dashed lines, respectively (see Table 1 for details).

4-Cyano-1-methylpyridinium perchlorate
Crystal data 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 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. H-atoms were placed in calculated positions (C-H = 0.95 -0.98 Å) and included as riding contributions with isotropic displacement parameters 1.2 -1.5 times those of the attached carbon atoms.