4-Cyano-1-methyl­pyridinium nitrate

The title mol­ecular salt, C₇H₇N₂⁺·NO₃⁻, displays an inter­penetrating sheet structure parallel to a with each sheet containing nearly coplanar cations and anions, each ion being bis­ected by a crystallographic mirror plane. C—H...O hydrogen bonds involving both ring and methyl H atoms in addition to cation–cation C—H...N hydrogen bonds (ring H to cyano N) serve to link the sheets together. In each set of parallel layers, the cations and anions stack with short distances of 3.094 (2) (between aligned nitrate N and pyridine N atoms) and 3.057 (2) Å (between a nitrate O atom and the ring centroid). This motif is strikingly similar to the one that features in the isomeric salt 2-cyano-1-methyl­pyridinium nitrate.

2-Cyano-1-methyl­pyridinium iodide

The cation in the title compound, C₇H₇N₂⁺·I⁻, is planar (r.m.s. deviation for the nine fitted non-H atoms = 0.040 Å). The crystal packing is best described as undulating layers of cations and anions associated via C—H...I inter­actions.

2-Cyano­anilinium iodide

The solid-state structure of the title salt, C₇H₇N₂^+.I⁻, consists of cation–anion sheets lying parallel to (110), with the components linked by N—H...I hydrogen bonds.