One-step preparation of ammonium-specified pyrazolium ionic liquids unveil the more popular pathway for the CO2 fixation: Integrated experimental and theoretical studies

Amino-specified pyrazolium ionic liquid (APEPzBr) is synthesized by two steps. It is interesting that the product of the first step ([EPzPNH 3 ]Br 2 ) could also catalyze the coupling reaction of carbon dioxide (CO 2 ) and epoxides under 70 °C along with 0.5 MPa CO 2 pressure, which is even more benign than APEPzBr. It is attributed to the strong ability of [EPzPNH 3 ]Br 2 to absorb CO 2 along with robust electrophilic activation, which is testified by density functional theory and 13 C NMR measurement. The difference between [EPzPNH 3 ]Br 2 and APEPzBr is further elucidated by electron localization function (ELF) and atoms in molecules (AIM).