Expanding the Origin of Stereocontrol in Propene Polymerization Catalysis

Originally developed on heterogeneous Ziegler-Natta (ZN) catalysts, the model of "chiral growing chain conformation" developed by Corradini to explain the origin of stereocontrol in propene polymerization was extended to all stereoselective polymerization catalysts. The idea that the chiral recognition is performed by the site-chirality thorough the conformation of growing chain represent the "unusual novelty" of ZN towards e.g. asymmetric catalysis in which a chiral host molecule recognize directly two enantiomeric guest molecules. In this paper, by using DFT calculations, we will show that the origin of the stereocontrol for the new generation of Hf(IV)-pyridylamido based catalysts is somewhat different and more similar to the asymmetric catalysis.