Discrete, Base-Free, Cationic Alkaline-Earth Complexes - Access and Catalytic Activity in the Polymerization of Lactide

Well-defined, base free cations of zinc and the alkaline-earth metals (Mg, Ca, Sr, Ba) supported by a multidentate phenolate ligand and stabilized by perfluorinated weakly coordinating counterions are readily available by simple procedures; the solid-state structures of the magnesium and calcium derivatives were elucidated. Upon treatment with an excess of iPrOH, these complexes generate highly efficient binary catalytic systems for the immortal ring-opening polymerization of L-lactide, yielding poly(L-lactide)s with controlled architectures and molecular features.