Liquid crystals of N,N′-dialkylimidazolium salts comprising palladium(II) and copper(II) ions

Metal-containing ionic liquid crystals of N,N'-dialkylimidazolium salts of Pd-II and CuII ([(CnH2n+1)(2)-im] [MCl4], n = 8, 10, 12, 14, 16, and 18 for M = Pd-II and n = 10, 12, 14, 16, and 18 for M = Cu-II) were prepared. Crystal structures of two compounds, [(C12H25)(2)-im](2)[PdCl4] and [(C12H25)(2)-im](2)[CuCl4] . H2O, have been characterized by single crystal X-ray diffraction. The cations of these two compounds adopt a U-shaped conformation and are packed in a highly interdigitated bilayer fashion. The square planar PdCl42- and distorted tetrahedral CuCl42- are sandwiched between the cationic bilayers individually. Both series of compounds exhibit a wide temperature range of SmA mesophase. Thermal decompositions are observed near the clearing tempertures. For the PdII series, decomposition generates palladium dicarbene and carbene-imidazole complexes. Ionic liquid crystals with different combinations of [(C18H37)(2)-im](2)[PdCl4], [(C18H37)(2)-im](2)[CuCl4]-H2O, and [(C18H37)(2)-im] Cl . H2O are good candidates for Pd-II/Cu-II catalyzed reactions carried out under partially ordered environments of ionic liquids.