Rare-earth/zinc heterometallic complexes containing both alkoxy-amino-bis(phenolato) and chiral salen ligands: synthesis and catalytic application for copolymerization of CO2 with cyclohexene oxide

Abstract

Ten rare-earth/zinc heterometallic complexes containing both alkoxy-amino-bis(phenolato) and chiral salen ligands were synthesized from the reactions of alkoxy-amino-bis(phenolato) rare-earth complexes with chiral salen zinc complexes via ligand redistribution and THF disassociation. Six of them were characterized by single-crystal X-ray diffraction, which showed 6-coordinate rare-earth and 5-coordinate zinc centres in the complexes. A primary catalytic application of these heterometallic complexes was studied, and it was found that samarium/zinc and dysprosium/zinc heterometallic complexes are highly efficient catalysts for copolymerization of CO₂ with cyclohexene oxide while the alkoxy-amino-bis(phenolato) samarium complex and chiral salen zinc complex show very low catalytic activity or no catalytic activity for this copolymerization.