The Effect of the Cation π‐Surface Area on the 3D Organization and Catalytic Ability of Imidazolium‐Based Ionic Liquids

The dichotomic nature of ionic liquids (ILs, simple solvents or supramolecular fluids) induced us to carry out a structural investigation of some mono‐ and dicationic ionic liquids using 1D and 2D NMR, resonance light scattering, and UV/Vis spectroscopy. Ionic liquids with different cation π‐surface areas were used, namely [bmim][NTf2], [Bzmim][NTf2], [Bzbim][NTf2], [p‐Xyl‐(bim)2][NTf2]2, and [m‐Xyl‐(bim)2][NTf2]2[bmim = 1‐butyl‐3‐methylimidazolium, Bzmim = 1‐benzyl‐3‐methylimidazolium, Bzbim = 1‐benzyl‐3‐butylimidazolium, NTf2= bis(trifluoromethansulfonyl)imide]. In order to verify to what extent the structural investigation, coupled with the determination of solvent parameters, could help to rationalize the effects of the solvent media on a given reaction, the thermally induced mononuclear rearrangement of heterocycles was studied. Variation of the cation structure has significant repercussions on the 3D structure of the ILs and on the effect they can exert on a given reaction.