Stereo-selectivity switchable ROP of rac-β-butyrolactone initiated by salan-ligated rare-earth metal amide complexes: the key role of the substituents on ligand frameworks

Abstract

A series of novel salan-ligated rare-earth metal amide complexes were prepared and employed as initiators for the ROP of rac-β-butyrolactone (rac-BBL). Tuning the substituents on the N atoms of the ligand frameworks from aromatic groups to aliphatic groups results in switching tacticity from iso-tactic to syndio-tactic in rac-BBL polymerization.