Titanium and zirconium complexes containing sterically hindered hydrotris(pyrazolyl)borate ligands: synthesis, structural characterization, and ethylene polymerization studies

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dc.contributor.authorGil, M. P.
dc.contributor.authorCasagrande, O. L.
dc.contributor.institutionUniversidade Federal do Rio Grande do Sul (UFRGS)
dc.contributor.institutionUniversidade Estadual Paulista (Unesp)
dc.date.accessioned2014-05-20T15:25:39Z
dc.date.available2014-05-20T15:25:39Z
dc.date.issued2004-01-15
dc.description.abstractThe synthesis, characterization and ethylene polymerization behavior of a set of Tp'MCl3 complexes (4, M = Ti, Tp' HB(3-neopentyl-pyrazolyl)(3)(-) (Tp(NP)); 5, M = Ti, Tp'= HB(3-tert-butyl-pyrazolyl)(3)(-) (Tp(tBu)); 6, M = Ti, Tp' = HB(3-phenyl-pyrazolyl)(3)(-) (Tp(Ph)); 7, M = Zr, Tp' = HB(3-phenyl-pyrazolyl)(3)(-) (Tp(ph)); 8, M = Zr, Tp' = HB(3-tert-butyl-pyrazolyl)(3)(-) (Tp(tBu))) is described. Treatment of these tris(pyrazolyl)borate Group IV compounds with methylalumoxane (MAO) generates active catalysts for ethylene polymerization. For the polymerization reactions performed in toluene at 60 degreesC and 3 atm of ethylene pressure, the activities varied between 1.3 and 5.1 X 10(3) g of PE/mol[M](.)h. The highest activity is reached using more sterically open catalyst precursor 4. The viscosity-average molecular weights ((M-v) over bar) of the PE's produced with these catalyst precursors varying from 3.57 to 20.23 x 10(5) gmol(-1) with melting temperatures in the range of 127-134 degreesC. Further polymerization studies employing 7 varying Al/Zr molar ratio and temperature of polymerization showed that the activity as well as the polymer properties are dependent on these parameters. In that case, higher activity was attained at 60 degreesC. The viscosity-average molecular weights of the polyethylene's decreases with increasing AI/Zr molar ratio. (C) 2003 Elsevier B.V. All rights reserved.en
dc.description.affiliationUFRGS, Inst Quim, Lab Mol Catalysis, BR-91509900 Porto Alegre, RS, Brazil
dc.description.affiliationUNESP, Inst Quim Araraquara, BR-14800900 Araraquara, SP, Brazil
dc.description.affiliationUnespUNESP, Inst Quim Araraquara, BR-14800900 Araraquara, SP, Brazil
dc.format.extent286-292
dc.identifierhttp://dx.doi.org/10.1016/j.jorganchem.2003.10.013
dc.identifier.citationJournal of Organometallic Chemistry. Lausanne: Elsevier B.V. Sa, v. 689, n. 2, p. 286-292, 2004.
dc.identifier.doi10.1016/j.jorganchem.2003.10.013
dc.identifier.issn0022-328X
dc.identifier.urihttp://hdl.handle.net/11449/36019
dc.identifier.wosWOS:000188598000003
dc.language.isoeng
dc.publisherElsevier B.V.
dc.relation.ispartofJournal of Organometallic Chemistry
dc.relation.ispartofjcr1.946
dc.rights.accessRightsAcesso restrito
dc.sourceWeb of Science
dc.subjecttris(pyrazolyl)borate ligandspt
dc.subjecttitanium and zirconiumpt
dc.subjectethylenept
dc.subjectpolymerizationpt
dc.titleTitanium and zirconium complexes containing sterically hindered hydrotris(pyrazolyl)borate ligands: synthesis, structural characterization, and ethylene polymerization studiesen
dc.typeArtigo
dcterms.licensehttp://www.elsevier.com/about/open-access/open-access-policies/article-posting-policy
dcterms.rightsHolderElsevier B.V.

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