Syntheses and Characterization of Unsymmetric Dicationic Salts Incorporating Imidazolium and Triazolium Functionalities

A series of both imidazolium- and triazolium-based unsymmetric dicationic salts with alkyl and polyfluoroalkyl
substituents were prepared and characterized. Most of them can be classified as ionic liquids (MP < 100 °C). Key
physical properties, such as melting point, thermal stability, density, and solubility in common solvents were determined
and were compared with those of the related monocationic imidazolium- or triazolium-based salts. The effects of
anions and substituents bonded to the triazolium and imidazolium cations on these properties were examined.
1-(3-Butyl-imidazolium-1-yl)methylene-(4-butyl-1,2,4-triazolium diiodide) (2d), the precursor of 1-(3-butylimidazolium-1-yl)methylene-(4-butyl-1,2,4-triazolium) bi[bis(trifluoromethanesulfonyl)amide] (3d), reacted with Pd(OAc)2 at 120
°C to generate a binuclear palladium(II) dicarbene complex. The palladium(II) complex was characterized by single-crystal X-ray diffraction analysis and was used as a catalyst precursor for palladium-catalyzed Heck cross-coupling
reactions in 3d. Preliminary results show that 3d could serve as both the solvent and catalyst support in the
catalytic reactions.