Catalyst nuclearity effects in olefin polymerization. enhanced activity and comonomer enchainment in ethylene + olefin copolymerizations mediated by bimetallic group 4 phenoxyiminato catalysts

Michael R. Salata, Tobin J. Marks

Research output: Contribution to journalArticle

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This contribution describes the synthesis, characterization, and catalytic implementation of the binuclear {2,7-di-[(2,6-diisopropylphenyl)imino]-1,8- naphthalenediolato group 4 metal complexes {1,8-(O) 0C 10H 4- 2,7-[CH=N(2,6- iPr 2C 6H 3)MZr2Cl 6(THF) 2 (FI 2-Zr 2) and { 1,8-(O)2C 10H 4-2,7-[CH=N(2,6-iPr 2C 6H 3)]2}Ti 2Cl 3(THF) (FI 2-Ti 2) in comparison to the mononuclear analogues {3- tBu-2-(O) C 6H 3CH=N(2,6- iPr 2C 6H 3)}ZrCl 3(THF) (FI- Zn) and {3- tBu-2-(O)C 6H 3CH=N(2,6- iPr 2C 6H 3)}TiCl 3(THF) (FI-TiO, in ethylene homopolymerization and ethylene + olefin copolymerization processes. The comonomers studied include 1-hexene, 1-octene, 1,5-hexadiene (1,5-HD), 1,4-pentadiene (1,4-PD), and highly hindered 1,1-disubstituted methylenecyclopentane (MCP) and methylenecyclohexane (MCH). In ethylene + 1-hexene copolymerizations, FI 2-Zr 2 enchains 1.5x more 1-hexene than FI-Zr 1, and FI 2-Ti 2 enchains 2.2x more 1-hexene than FI-Ti 1. While ethylene + 1,5-HD and ethylene + 1,4- PD copolymerizations mediated by FI 2-Zr 2 and FI-Zr 1 produce ethylene + 1,4-PD and ethylene + 1,5-HD copolymers at respectable activities, FI 2-Ti 2 and FI-Ti 1 are virtually inactive. While MCP and MCH are efficiently coenchained with ethylene via a ring-unopened pathway by both FI 2-Ti 2 and FI-Ti 1, FI 2-Zr 2 and FI-Zr 1 produce only polyethylene. These examples represent the first olefin copolymerizations reported for monophenoxyiminato group 4 complexes, and in general the bimetallic catalysts incorporate between 1.8x and 3.4x more comonomer in ethylene + olefin copolymerizations than their monometallic counterparts. In comparison to mono- and binuclear group 4 constrained geometry catalysts (CGCs), the mono- and binuclear FI catalysts: (1) enchain significantly greater densities of a-olefins, (2) display enhanced binuclear catalyst polymerization activity versus their mononuclear analogues, and (3) produce predominantly linear polyethylenes as opposed to the branched polyethylenes produced by CGCs.

Original languageEnglish
Pages (from-to)1920-1933
Number of pages14
Issue number6
Publication statusPublished - Mar 24 2009


ASJC Scopus subject areas

  • Organic Chemistry
  • Polymers and Plastics
  • Inorganic Chemistry
  • Materials Chemistry

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