Ethylene-bridged pseudo-Cs symmetric ansa-zirconocene complexes

Synthesis, structures and propylene polymerization behavior

Min Hyung Lee, Je Woo Park, Chang Seop Hong, Seong Ihl Woo, Youngkyu Do

Research output: Contribution to journalArticle

17 Citations (Scopus)

Abstract

The ethylene-bridged pseudo-Cs symmetric ansa-zirconocene complexes, (1-fluorenyl-2-cyclopentadienylethane)zirconium dichloride (5a) and (1-fluorenyl-2-tetramethylcyclopentadienylethane)zirconium dichloride (5b), were synthesized and their molecular structures have been determined by single crystal X-ray diffraction studies. The complex 5a is very active toward propylene polymerization in the presence of methylaluminoxane (MAO), affording polypropylene with good syndiotacticity. In comparison with the known syndiotactic polypropylene catalytic system iPr(fluorenyl)(cyclopentadienyl)ZrCl2/MAO, 5a/MAO system is better in thermal stability, higher in activity and lower in syndiotacticity under the identical polymerization conditions. On the other hand, 5b/MAO system shows low activity and produces nearly atactic polypropylene with low molecular weight, which could be attributed to the increased electron density and steric bulkiness around the metal center.

Original languageEnglish
Pages (from-to)37-47
Number of pages11
JournalJournal of Organometallic Chemistry
Volume561
Issue number1-2
Publication statusPublished - 1998 Jun 30
Externally publishedYes

Fingerprint

Polypropylenes
propylene
polypropylene
Polymerization
Propylene
Ethylene
ethylene
polymerization
dichlorides
Zirconium
synthesis
low molecular weights
Molecular Structure
X-Ray Diffraction
Molecular structure
Carrier concentration
Thermodynamic stability
thermal stability
molecular structure
Thermodynamic properties

Keywords

  • Ethylene-bridged
  • Pseudo-C symmetry
  • Zirconocene

ASJC Scopus subject areas

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

Cite this

Ethylene-bridged pseudo-Cs symmetric ansa-zirconocene complexes : Synthesis, structures and propylene polymerization behavior. / Lee, Min Hyung; Park, Je Woo; Hong, Chang Seop; Woo, Seong Ihl; Do, Youngkyu.

In: Journal of Organometallic Chemistry, Vol. 561, No. 1-2, 30.06.1998, p. 37-47.

Research output: Contribution to journalArticle

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AU - Woo, Seong Ihl

AU - Do, Youngkyu

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AB - The ethylene-bridged pseudo-Cs symmetric ansa-zirconocene complexes, (1-fluorenyl-2-cyclopentadienylethane)zirconium dichloride (5a) and (1-fluorenyl-2-tetramethylcyclopentadienylethane)zirconium dichloride (5b), were synthesized and their molecular structures have been determined by single crystal X-ray diffraction studies. The complex 5a is very active toward propylene polymerization in the presence of methylaluminoxane (MAO), affording polypropylene with good syndiotacticity. In comparison with the known syndiotactic polypropylene catalytic system iPr(fluorenyl)(cyclopentadienyl)ZrCl2/MAO, 5a/MAO system is better in thermal stability, higher in activity and lower in syndiotacticity under the identical polymerization conditions. On the other hand, 5b/MAO system shows low activity and produces nearly atactic polypropylene with low molecular weight, which could be attributed to the increased electron density and steric bulkiness around the metal center.

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