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.