Zinc and aluminum complexes of chiral ligands: Synthesis, characterization and application to rac-lactide polymerization

Abstract The crystalline complexes L 2 Zn ( 1 ), L 3 Al ( 2 ), L ′ 2 Zn ( 3 ) and L 'AlMe 2 ( 4 ) were synthesized from the reactions of the corresponding chiral ligands ( S ) N -(2-pyrrolylmethylene)-1-phenylethylamine ( HL ) or ( S ) N -(2-pyrrolylmethyl)-1-phenylethanamine ( HL′ ) and diethylzinc or trimethylaluminum, respectively. Complexes 1 – 4 were well characterized by 1 H NMR, 13 C NMR spectroscopy, elemental analyses and single crystal X-ray crystallography. Furthermore, the catalytic activities toward ring-opening polymerization (ROP) of rac -lactide have been investigated and all of the complexes can be used as initiators to give the isotactic-rich polylactides.