Coordination copolymerization of severely encumbered isoalkenes with ethylene: Enhanced enchainment mediated by binuclear catalysts and cocatalysts

Hongbo Li, Liting Li, David J. Schwartz, Matthew V. Metz, Tobin J. Marks, Louise Liable-Sands, Arnold L. Rheingold

Research output: Contribution to journalArticle

81 Citations (Scopus)


This contribution describes the implementation of the binuclear organotitanium "constrained geometry catalysts" (CGCs), (μ-CH 2CH2-3,3′){(η5-indenyl)[1-Me 2Si(tBuN)](TiMe2)}2[EBICGC(TiMe 2)2; Ti2] and (μ-CH2-3,3′) {(η5-indenyl)[1-Me2Si(tBuN)](TiMe 2)}2[MBICGC(TiMe2)2; C1-Ti 2], in combination with the bifunctional bisborane activator 1,4-(C6F5)2BC6F4B(C 6F5)2 (BN2) in ethylene + olefin copolymerization processes. Specifically examined are the classically poorly responsive 1,1-disubstituted comonomers, methylenecyclopentane (C), methylenecyclohexane (D), 1,1,2-trisubstituted 2-methyl-2-butene (E), and isobutene (F). For the first three comonomers, this represents the first report of their incorporation into a polyethylene backbone via a coordination polymerization process. C and D are incorporated via a ring-unopened pathway, and E is incorporated via a novel pathway involving 2-methyl-1 -butene enchainment in the copolymer backbone. In ethylene copolymerization, Ti 2 + BN2 enchains ∼2.5 times more C, ∼2.5 times more D, and ∼2.3 times more E than the mononuclear catalyst analogue [1-Me2Si(3-ethylindenyl)-(tBuN)]TiMe2 (Ti 1) + B(C6F5)3 (BN) under identical polymerization conditions. Polar solvents are found to weaken the catalyst-cocatalyst ion pairing, thus influencing the comonomer enchainment selectivity.

Original languageEnglish
Pages (from-to)14756-14768
Number of pages13
JournalJournal of the American Chemical Society
Issue number42
Publication statusPublished - Nov 1 2005


ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

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