4-Cyano-1-methyl­pyridinium iodide

In the crystal structure of the title compound, C(7)H(7)N(2) (+)·I(−), the cations form inversion-related dimers via weak pairwise C—H⋯N hydrogen bonds. In the dimers, the pyridinium rings are parallel to one another with their mean planes separated by a normal distance of ca 0.28 Å. Weak C—H⋯N inter­actions between adjacent dimers generate a layer lying parallel to (10-1). The remaining H atoms form C—H⋯I inter­actions, which link the layers into a three-dimensional structure.