N-Heterocyclic Carbene Stabilized Indenyl Scandium Di-Alkyl Complex: Preparation Of Ultra-High Molecular Weight Polyolefin

By using (i)Pr(2)Im as a Lewis base ligand, beta-H elimination reactions of propylene polymerization were suppressed at-30 degrees C. Polypropylene and its block copolymers with ethylene possessing ultra-high molecular weights (M-n > 1,000,000 g/mol) were successfully obtained in high TOFs (PP > 10(4) mol molSc(-1) h(-1)). DFT calculations suggested that the delocalized electrons in the strongly conjugated system of (i)Pr(2)Im could significantly reduce the electro positivity of active sites. This method provides a convenient strategy for tuning the electronic properties of active sites.