Novel Chlorotitanium Complexes Containing Chiral Tridentate Schiff Base Ligands for Ring-Opening Polymerization of Lactide

The selective synthesis of tri- and dichlorotitanium species containing chiral tridentate Schiff base ligands, derived from (1R,2S)-(−)-1-aminoindanol, was achieved by changing the solvent. Single-crystal X-ray analyses reveal that chlorotitanium complexes are monomeric and octahedral with the meridional occupation of the Schiff base. Although the chlorotitanium complexes lack typical initiating groups such as alkoxides or amides, they are effective catalysts for the controlled ring-opening polymerization of l-lactide (l-LA) as shown by the linearity of the molecular weight vs [l-LA]/[Ti] ratio plot as well as very narrow polydispersity index values.