Rotating Benzyl Substituent in ansa-Bis(indenyl)zirconocenes Controls Propene Polymerization

A series of benzyl-substituted, dual-site ansa-metallocenes were synthesized and characterized. Their isolated rac- and meso-diastereomers were studied in propene polymerization after methylaluminoxane or borate activation. Catalysts’ polymerization behavior were investigated in various polymerizati...

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Published inOrganometallics Vol. 29; no. 18; pp. 4018 - 4024
Main Authors Puranen, Arto, Linnolahti, Mikko, Piel, Tanja, Elo, Pertti, Mutikainen, Ilpo, Pakkanen, Tapani, Löfgren, Barbro, Aitola, Erkki, Seppälä, Jukka, Leskelä, Markku, Repo, Timo
Format Journal Article
LanguageEnglish
Published WASHINGTON American Chemical Society 27.09.2010
Amer Chemical Soc
Subjects
Chemistry
Chemistry, Inorganic & Nuclear
Chemistry, Organic
Physical Sciences
Science & Technology
CATIONIC ZIRCONOCENE COMPLEXES
PHENYL COORDINATION
ETHYLENE
MONOMER CONCENTRATION
POLYPROPYLENE
POLYPROPENES
METALLOCENE CATALYSTS
DIASTEREOMERS
MICROSTRUCTURE
ELASTOMERIC POLY(PROPYLENE)
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Summary:A series of benzyl-substituted, dual-site ansa-metallocenes were synthesized and characterized. Their isolated rac- and meso-diastereomers were studied in propene polymerization after methylaluminoxane or borate activation. Catalysts’ polymerization behavior were investigated in various polymerization conditions, and produced polypropenes (PPs) were characterized with NMR, GPC, and DSC. The rac- and meso-diastereomers of these unsymmetric catalysts bearing a SiMe2 bridge produced PP with similar activity, tacticity, and molar mass. According to quantum chemical calculations, the benzyl group in the catalysts can rotate, having significant energy minima. The reason that the diastereomers produce PP with similar molar mass is linked to these local energy minima and is further discussed.
Bibliography:Academy of Finland (AKA)
ISSN:0276-7333
1520-6041
DOI:10.1021/om9009262