Metallocene complexes as homogeneous catalysts in olefin polymerization
- Universitaet Bayreuth (Germany)
Ansa metallocene dichloride complexes of titanium, zirconium, and hafnium can be activated by methyl aluminoxane (MAO) to give excellent catalysts for the homogeneous polymerization of ethylene and propylene. The symmetry of the corresponding metallocene dichloride complexes is essential for the stereospecific polymerization of propylene (isotactic, syndiotactic or atactic). The application of fluorenyl groups instead of cyclopentadienyl groups greatly increases the activity of the catalysts. The first ansa bis(fluorenyl) complexes of zirconium and hafnium, (C{sub 13}H{sub 8}-C{sub 2}H{sub 4}-C{sub 13}H{sub 8})MCl{sub 2} (M = Zr, Hf), have been prepared. It was found that after the activation by MAO the zirconium derivative demonstrates a very high activity. Several models are presented in order to discuss the mechanism of the polymerization.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 182226
- Journal Information:
- Russian Chemical Bulletin, Journal Name: Russian Chemical Bulletin Journal Issue: 1 Vol. 44; ISSN 1066-5285; ISSN RCBUEY
- Country of Publication:
- United States
- Language:
- English
Similar Records
Olefin polymerization at bis(pentamethylcyclopentadienyl) zirconium and -hafnium centers: Chain-transfer mechanisms
Chiral C{sub 1}-symmetric group 4 metallocenes as catalysts for stereoregular {alpha}-olefin polymerization. Metal, ancillary ligand, and counteranion effects