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Abstract <p>The paper reports the <sup>1</sup>H NMR characterization results for the products of <i>rac-</i>Et(2-MeInd)<sub>2</sub>ZrMe<sub>2</sub> activation by diisobutylaluminum aryloxide 2,6-<sup><i>t</i></sup>Bu<sub>2</sub>PhO-)Al<sup><i>i</i></sup>Bu<sub>2</sub> (hereinafter referred to as Al<sup><i>i</i></sup>Bu<sub>2</sub>(OAr)), with and without olefins (1-hexene/ethylene/propylene). The olefin-free reaction between the catalyst and Al<sup><i>i</i></sup>Bu<sub>2</sub>(OAr) caused the decomposition of dimethylated zirconocene with liberation of methane and isobutene, likely due to the formation of a cationic complex [<i>rac-</i>Et(2-MeInd)<sub>2</sub>ZrMe]<sup>+</sup>[MeAl<sup><i>i</i></sup>Bu<sub>2</sub>(OAr)]<sup>–</sup>, unstable at room temperature. In the presence of 1-hexene, <i>rac-</i>Et(2-MeInd)<sub>2</sub>ZrMe<sub>2</sub> was effectively activated by diisobutylaluminum aryloxide to generate a catalytically active intermediate with a growing polymer chain—[<i>rac-</i>Et(2-MeInd)<sub>2</sub>ZrCH<sub>2</sub>CH(<sup><i>i</i></sup>Bu)Pol]<sup>+</sup>· [MeAl<sup><i>i</i></sup>Bu<sub>2</sub>(OAr)]<sup><i>–</i></sup>—and to form polyhexene. After complete depletion of hexene-1, the working catalyst was deactivated with the formation of <i>rac-</i>Et(2-MeInd)<sub>2</sub>Zr(H)CH<sub>2</sub>CH(<sup><i>i</i></sup>Bu)Pol, MeAl<sup><i>i</i></sup>Bu(OAr), and isobutene. In the presence of ethylene and propylene, the <sup>1</sup>H NMR signals of the olefins weakened over time, and insoluble polymer particles accumulated on the tube walls. A reaction mechanism was proposed for the <i>rac</i>-Et(2-MeInd)<sub>2</sub>ZrMe<sub>2</sub>/Al<sup><i>i</i></sup>Bu<sub>2</sub>(OAr) system, accounting for pathways both with and without olefins.</p>

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1H NMR Characterization of rac-Et(2-MeInd)2ZrMe2 Activation by Diisobutylaluminum Aryloxide (2,6-tBu2PhO-)AliBu2

  • 期刊论文

  • 发表日期：

    2025年7月1日

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  • E. E. Faingol’d,
  • I. V. Zharkov,
  • S. L. Saratovskikh,
  • A. N. Panin,
  • N. N. Lashmanov,
  • D. S. Vinnikov,
  • A. V. Chernyak,
  • N. M. Bravaya

摘要

Abstract

The paper reports the 1H NMR characterization results for the products of rac-Et(2-MeInd)2ZrMe2 activation by diisobutylaluminum aryloxide 2,6-tBu2PhO-)AliBu2 (hereinafter referred to as AliBu2(OAr)), with and without olefins (1-hexene/ethylene/propylene). The olefin-free reaction between the catalyst and AliBu2(OAr) caused the decomposition of dimethylated zirconocene with liberation of methane and isobutene, likely due to the formation of a cationic complex [rac-Et(2-MeInd)2ZrMe]+[MeAliBu2(OAr)]–, unstable at room temperature. In the presence of 1-hexene, rac-Et(2-MeInd)2ZrMe2 was effectively activated by diisobutylaluminum aryloxide to generate a catalytically active intermediate with a growing polymer chain—[rac-Et(2-MeInd)2ZrCH2CH(iBu)Pol]+· [MeAliBu2(OAr)]–—and to form polyhexene. After complete depletion of hexene-1, the working catalyst was deactivated with the formation of rac-Et(2-MeInd)2Zr(H)CH2CH(iBu)Pol, MeAliBu(OAr), and isobutene. In the presence of ethylene and propylene, the 1H NMR signals of the olefins weakened over time, and insoluble polymer particles accumulated on the tube walls. A reaction mechanism was proposed for the rac-Et(2-MeInd)2ZrMe2/AliBu2(OAr) system, accounting for pathways both with and without olefins.