Crystal structure of 2-cyano-1-methylpyridinium perchlorate

The asymmetric unit of the title salt, C7H7N2 +·ClO4 −, comprises two independent formula units. The solid-state structure comprises corrugated layers of cations and of anions, approximately parallel to (010). The supramolecular layers are stabilized and connected by C—H⋯O hydrogen bonding to consolidate a three-dimensional architecture. A close pyridinium–perchlorate N⋯O contact [2.867 (5) Å] is noted. The crystal was refined as an inversion twin.


S1. Comment
The asymmetric unit comprises two independent formula units. A portion of the C-H···O hydrogen bonding network which aids the packing of the several ions is shown in Fig. 1 with a fuller depiction appearing in Figs 2 and 3. The solid state structure consists of corrugated layers of cations and anions formed by C-H···O hydrogen bonding between them and approximately parallel to (010). These layers are held to one another by additional C-H···O interactions. The overall structure is essentially the same as found for the tetrafluoroborate salt (Vaccaro et al., 2015). at about -5° over several months to form crystals suitable for single-crystal X-ray diffraction.

S3. Refinement
H-atoms attached to carbon were placed in calculated positions (C-H = 0.95 -0.98 Å). All were included as riding contributions with isotropic displacement parameters 1.2 -1.5 times those of the attached atoms. The crystal was refined as a 2-component twin.

Figure 1
Perspective view of the asymmetric unit with 50% probability ellipsoids. C-H···O interactions are shown by dotted lines.

Figure 2
Packing viewed down the a axis showing an edge view of two corrugated layers and the C-H···O interaction (dotted line) holding them together.

Figure 3
Packing viewed down the b axis providing a plan view of the corrugated sheets with C-H···O interactions shown as dotted lines.

Special details
Experimental. The diffraction data were obtained from 3 sets of 400 frames, each of width 0.5° in ω, collected at φ = 0.00, 90.00 and 180.00° and 2 sets of 800 frames, each of width 0.45° in φ, collected at ω = -30.00 and 210.00°. The scan time was 15 sec/frame. Analysis of 3152 reflections having I/σ(I) > 13 and chosen from the full data set with CELL_NOW (Sheldrick, 2008a) showed the crystal to belong to the monoclinic system and to be twinned by a 180° rotation about c*. The raw data were processed using the multi-component version of SAINT under control of the twocomponent orientation file generated by CELL_NOW. Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s 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 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 attached to carbon were placed in calculated positions (C-H = 0.95 -0.98 Å). All were included as riding contributions with isotropic displacement parameters 1.2 -1.5 times those of the attached atoms. Refined as a 2-component twin.