Ionic liquid-derived zinc tetrahalide complexes: structure and application to the coupling reactions of alkylene oxides and CO2

Various alkylene carbonates have been prepared in high yields by the coupling reactions of alkylene oxides with CO2 in the presence of a dialkylimidazolium zinc tetrahalide complex, prepared from imidazolium halides and zinc halides. The single crystal X-ray diffraction analysis of an active species (1,3-dimethylimidazolium)2ZnBr2Cl2 showed that two 1,3-dimethylimidazolium cations were paired with a dibromodichloro zincate dianion.