A series of ether-derivatized imidazolium halides have been prepd. and characterized. Contrary to literature reports, they are all cryst. solids and have m.ps. well above room temp. (50-100 °C). Single crystals of the imidazolium salts, obtained in situ by slow cooling from their molten state to room temp., were analyzed by X-ray crystallog., revealing various anion-cation interactions in the solid state. Exchange of the halides with [Tf2N]- yielded room temp. ionic liqs. with viscosities that are comparable to related 1-alkyl-3-methylimidazolium ionic liqs. D. functional theory combined with IR spectroscopy has been used to analyze the role of functionalization of the imidazolium side chain on the formation of the mol. and supramol. structure of the compds. and its possible impact on their phys. properties.