Living Polymerization of Propylene with ansa-Dimethylsilylene(fluorenyl)(cumylamido) Titanium Complexes

Substituent Effects of Phenyl Group on Silylene Bridge in Stereospecific Polymerization of Propylene with C₁-Symmetric Ansa-Silylene(fluorenyl)(amido) Dimethyl Titanium Complexes

A C₁-symmetric (methylphenyl)silylene-bridged (fluorenyl)(naphthylamido) titanium complex (1) and (diphenyl)silylene-bridged (fluorenyl)(naphthylamido) titanium complex (2) were synthesized and characterized by ¹H NMR, element analysis, and X-ray crystal analysis. The coordination mode of the fluorenyl ligand to the titanium metal is an η³ manner in each complex. These complexes were applied for propylene polymerization using dried modified methyaluminoxane (dMMAO) as a cocatalyst under different propylene pressures in a semi batch-type method. The catalytic activity was strongly dependent on the structure of the complex and the propylene pressure, where complex 1 exhibited the highest activity (600 kg mol-1·h-1) under a propylene pressure of 8.0 atm to produce high molecular weight polypropylene. The polypropylenes obtained were syndiotactic-rich with an rr value of 0.50, indicating that the silylene bridge was not efficient for the isospecificity of a constrained geometry catalyst (CGC). The mechanical properties of the resulting polymers depended on their microstructure.

Efficient control of ethylene–norbornene copolymerization behavior of a fluorenylamido-ligated titanium complex: substituent effects of the amido ligand and copolymer properties

Copolymerization behavior of ethylene and norbornene was controlled using a (fluorenyl)(amido)titanium complex bearing a cumyl-amido ligand.