Robust pyrrole-Schiff base Zinc complexes as novel catalysts for the selective cycloaddition of CO2 to epoxides

A series of Zn (II) complexes with nitrogen Schiff base ligands (NSB) has been synthesized from pyrrole carboxaldehyde. The prepared were fully characterized. Single crystal X-ray diffraction analysis showed various coordination modes, as monomers or helical dimers according to the number available atoms surrounding zinc cation. complex structure optimizations carried out using density functional theory (DFT) ADF program and dimerization energies temperature effect examined. used Lewis acids (LA) combined tetrabutylammonium halides (N4BuX) bases (LB), for catalytic valorization CO2 into cyclic carbonates. new momomeric Zn-NSB was chosen study influence different reaction parameters (temperature, pressure, LA/LB molar ratio, catalyst amount). Thus, optimized conditions afforded solvent-free selective formation styrene carbonate in good yields (up 98 %) allowed reuse this Zn-NSB/N4BuX system without any loss activity.