In the cation of the title mol-ecular salt, C15H18NO+·Br-, the pyridinium and phenyl rings are inclined to one another by 11.80 (8)°. In the crystal, the Br- anion is linked to the cation by a C-H⋯Br hydrogen bond. The cations stack along the b-axis direction and are linked by further C-H⋯Br inter-actions, and offset π-π inter-actions [inter-centroid distances = 3.5733 (19) and 3.8457 (19) Å], forming slabs parallel to the ab plane. The effects of the C-H⋯X- inter-action on the NMR signals of the ortho- and meta-pyridinium protons in a series of related ionic liquids, viz. 4-methyl-1-(4-phen-oxy-but-yl)pyridin-1-ium salts, are reported and discussed.
Keywords: crystal structure; halide; hydrogen bonding; ionic liquids; pyridinium salts; π–π interactions.