New sterically hindered unbridged zirconocene complexes with 1,2-diphenylcyclopentadienyl ligands: synthesis, structure and properties as olefin polymerization catalysts
| Autor: | Congxi Chen, Ying Mu, Wei-Ming Bu, Huimin Zhai, Han Hong, Yuetao Zhang, Ligang Zhao, Fan Zhang |
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| Rok vydání: | 2000 |
| Předmět: |
Steric effects
Zirconium Olefin fiber Organic Chemistry Methylaluminoxane chemistry.chemical_element Biochemistry Catalysis Inorganic Chemistry chemistry.chemical_compound chemistry Polymerization Polymer chemistry Materials Chemistry Molar mass distribution Lithium Physical and Theoretical Chemistry |
| Zdroj: | Journal of Organometallic Chemistry. 613:68-76 |
| ISSN: | 0022-328X |
| DOI: | 10.1016/s0022-328x(00)00498-8 |
| Popis: | New unbridged zirconocene complexes, bis(1,2-diphenylcyclopentadienyl)zirconium dichloride ( 3 ) and bis(4-methy-1,2-diphenylcyclopentadienyl)zirconium dichloride ( 4 ) have been synthesized in high yield by reaction of ZrCl 4 with the lithium salt of 1,2-diphenylcyclopentadiene ( 1 ) or 4-methyl-1,2-diphenylcyclopentadiene ( 2 ), respectively. X-ray crystallographic analysis reveals both complexes are in racemic-like conformation with near C 2 symmetry in solid state. When activated with methylaluminoxane (MAO), 3 and 4 exhibit moderate catalytic activities for ethylene polymerization at relatively low Al:Zr ratios, producing high molecular weight (>10 6 ) polyethylenes with high melting transition temperatures. Atactic propylene oligomers with average molecular weight of ∼10 3 g mol −1 were produced by both 3 and 4 at relatively high catalytic activities upon activation with MAO. |
| Databáze: | OpenAIRE |
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