Isotactic-Specific Polymerization of Propene by a C-s-Symmetric Zirconium(IV) Complex Bearing a Dianionic Tridentate [-NNN-] Amidomethylpyrrolidepyridine Ligand

ABSTRACT: The synthesis and characterization of a new tridentate amidomethylpyrrolidepyridine ligand (LigH2) and of the corresponding LigZr(NMe2)2 complex (1) are described. Characterization of 1 by single-crystal X-ray diffraction analysis showed a slightly distorted square-pyramidal geometry. Variable-tempera- ture NMR analysis suggested that 1 adopts a Cs-symmetric structure in solution. Complex 1 in combination with AliBu2H and methylalumoxane afforded a highly active single-site catalyst for the polymerization of ethylene and propene, producing ultrahigh molecular weight linear polyethylene and isotactic polypropylene via an “enantiomorphic sites” mechanism of steric control.