Catalyst Nuclearity Effects in Olefin Polymerization

Michael R Salata

doi:https://doi.org/10.21985/N2Z142

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Catalyst Nuclearity Effects in Olefin Polymerization

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The new binuclear organo-zirconium and -titanium metal complexes {2,7-di-[(2,6diisopropylphenyl)imino]-1,8-naphthalenediolato group 4 metal complexes {1,8-(O)2C10H4-2,7[CH=N(2,6-iPr2C6H3)]2}Zr2Cl6(THF)2 (FI2-Zr2) and {1,8-(O)2C10H4-2,7-[CH=N(2,6- i 2 t Pr2C6H3)]2}Ti2Cl6(THF)2 (FI -Ti2) are compared to the mononuclear analogues {3- Bu-2(O)C6H3CH=N(2,6-iPr2C6H3)}ZrCl3(THF) (FI-Zr1) and {3-tBu-2-(O)C6H3CH=N(2,6- i Pr2C6H3)}TiCl3(THF) (FI-Ti1), respectively, in ethylene polymerization 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, FI2-Zr2 enchains 1.5x more 1-hexene than FI-Zr1, and FI2-Ti2 enchains 2.2x more 1-hexene than FI-Ti1. While ethylene + 1,5-HD and ethylene + 1,4-PD copolymerizations mediated by FI2-Zr2 and FI-Zr1 produce ethylene + 1,4-PD and ethylene + 1,5-HD copolymers at respectable activities, FI2-Ti2 and FI-Ti1 are virtually inactive. While MCP and MCH are efficiently co-enchained with ethylene via a ring-unopened pathway by both FI2-Ti2 and FI-Ti1, FI2-Zr2 and FI-Zr1 produce only polyethylene. These examples represent the first olefin copolymerizations reported for mono-phenoxyiminato group 4 complexes, and in general the bimetallic catalysts incorporate between 1.8x - 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 α-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.

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