New air-stable zinc complexes formed from cyanoacrylate- and methylenemalonate-based [N2O2]-ligands and their role as catalysts in epoxide-CO2 coupling

The synthesis of a range of zinc complexes based on ligands displaying an N2O2-framework with cyanoacrylate and/or malonate functionality is presented. Some complexes could be examined via X-ray diffraction on single crystals, giving interesting insights into the structures of these zinc compounds, some of them building coordination polymers. The zinc complexes are highly active in the catalytic conversion of propylene oxide with CO2 to afford propylene carbonate. The study of this class of complexes leads to reactivity trends showing that ligands with aromatic diamino linkers and malonate fragments display the highest catalytic activity under mild conditions.