Novel Olefin Polymerization Pre-Catalyst Bearing an Inversely-Polarized Phosphaalkene Ethenolate Monoanionic Bidentate Ligand and its Polymerization Studies

The synthesis and structure elucidation of the first monoanionic bidentate ligand bearing an inversely-polarized phosphaalkene, its precursors and the first titanium complex bearing such ligand are herein reported. Single-crystal X-ray studies of the titanium complex confirmed the coordination of the bidentate ligand using the phosphaalkene phosphorus and ethenolate oxygen atoms with a strong evidence that there is charge delocalization through the metallocycle and the imidazole ring. The thermal stability of the phosphaalkeneethenolate ligand and the titanium complex at high temperature is reported. The new titanium complex displayed an activity for ethylene polymerization up to 9.2 kg PE mol cat1 h1. The polyethylene produced was linear with a low degree of branching, an average molecular weight of ~ 6000 g mol1 and a Tm of 130.0 C.