Supramolecular organization in lead bromide salts of imidazolium-based ionic liquids

By heating imidazolium bromide-based ionic liquids with lead(II) salts under ionothermal conditions, we have been able to obtain two imidazolium bromoplumbates, (EMIm)PbBr3, I, and (BMIm)(2)PbBr4, II, where EMIm and BMIm stand for 1-ethyl-3-methyl and 1-butyl-3-methyl imidazolium cations respectively. Interestingly, both these compounds exhibit unusual supramolecular organization wherein dialkylimidazolium cations arrange themselves in a cylindrical fashion giving rise to channel structures. The bromoplumbate anions reside in the channels. The lead(II) cation exhibits either hemi- or holodirected coordination geometry.