Ring-opening polymerization of cyclic esters by an enantiopure heteroscorpionate rare earth initiator.

With a sting in its tail: An enantiopure neodymium complex (see scheme) acts as an efficient single-site initiator for the controlled ring-opening polymerization of rac-lactide, forming isotactic polyester. The heteroscorpionate complex was characterized spectroscopically and by X-ray diffraction.