Syntheses of methylene-bridged ansa-zirconocene complexes and copolymerization studies of ethylene and norbornene

Si Geun Lee, Sung Don Hong, Young Whan Park, Boong Goon Jeong, Dae Woo Nam, Hye Young Jung, Hyosun Lee, Kwang Ho Song

Research output: Contribution to journalArticle

15 Citations (Scopus)

Abstract

Methylene-bridged ansa-metallocene complexes bearing substituents on the cyclopentadienyl (Cp) and fluorenyl (Flu) moieties, namely methylene[9-(2,7-di-tert-butyl)fluorenyl (2-(1,3-dimethylcyclopentadienyl)]zirconium dichloride (1a) and its analogue, methylene [(9-(2,7-di-tert-butyl)fluorenyl (2-(1-methyl-3-phenyl)cyclopentadienyl) ]zirconium dichloride (2a), have been prepared from (2,7-di-tert-butyl)-9-prop-2-ynyl-9H-fluorene (2). This procedure includes the use of 3-bromo-1-propyne which affords the methylene bridging unit by way of an intermolecular Pauson-Khand reaction in which norbornadiene and a pendant alkyne cyclize to form a ring that later becomes a substituted cyclopentadienyl group. Ethylene-norbornene (E-N) copolymerization was then carried out using these new complexes (1a and 1b) in the presence of methylaluminoxane (MAO) as a cocatalyst; these activities can be compared to that of isopropylene[9-fluorenyl-cyclopentadienyl]zirconium dichloride (3a). The activity of catalyst 1a was comparable to that of 3a but much higher than that of 2a. In addition, 1a shows higher norbornene insertion performance, and gives an E-N copolymer with a higher glass transition temperature (Tg) than 2a under identical conditions; both 1a and 2a give a lower Tg polymer than 3a does.

Original languageEnglish
Pages (from-to)2586-2592
Number of pages7
JournalJournal of Organometallic Chemistry
Volume689
Issue number16
DOIs
Publication statusPublished - 2004 Aug 15

Keywords

  • Ethylene norbornene copolymerization
  • Glass transition temperature (T)
  • MAO
  • ansa-Zirconocene

ASJC Scopus subject areas

  • Biochemistry
  • Physical and Theoretical Chemistry
  • Organic Chemistry
  • Inorganic Chemistry
  • Materials Chemistry

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