Positional Electronic Effects in Iminopyridine-N-oxide Nickel Catalyzed Ethylene Polymerization†,Chinese Journal of Chemistry

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Positional Electronic Effects in Iminopyridine-N-oxide Nickel Catalyzed Ethylene Polymerization†
Chinese Journal of Chemistry ( IF 5.5 ) Pub Date : 2021-02-07 , DOI: 10.1002/cjoc.202000712
Mingjun Chi ₁ , Ao Chen ₁ , Wenmin Pang ₁ , Chen Tan ₂ , Changle Chen ₁

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A series of dibenzhydryl-based iminopyridine-N-oxide ligands bearing a range of electron-donating or -withdrawing substituents (OMe, H, and NO₂) and corresponding nickel pre-catalysts are prepared and characterized. The substituents are installed at different positions on the ligand structure, including 4-position of the pyridine-N-oxide moiety (position X) and 4-position of the aniline moiety (position Y). These nickel pre-catalysts are highly active in ethylene polymerization with the addition of very little amount of aluminum cocatalysts, leading to the formation of polyethylenes with molecular weights of well above one million. Electron-donating substituents make the catalysts sensitive to polymerization temperature. In contrast, the catalysts bearing electron-withdrawing NO₂ substituents show relatively steady performances at different temperatures. Most importantly, we demonstrate that different substituents and different positions both play important roles in determining the properties of nickel catalysts. This provides an alternative strategy for the future design of high-performance polymerization catalyst.

中文翻译：

氨基吡啶-N-氧化物镍催化的乙烯聚合中的位置电子效应†

制备和表征了一系列带有一系列给电子或吸电子取代基（OMe，H和NO ₂）的二苯并氢基的亚氨基吡啶-N-氧化物配体和相应的镍预催化剂。取代基安装在配体结构的不同位置，包括吡啶-N的4位-氧化物部分（位置X）和苯胺部分的4位（位置Y）。这些镍预催化剂在乙烯聚合中具有很高的活性，并且添加了很少量的铝助催化剂，从而导致形成分子量远高于一百万的聚乙烯。给电子的取代基使催化剂对聚合温度敏感。相反，带有吸电子NO ₂取代基的催化剂在不同温度下表现出相对稳定的性能。最重要的是，我们证明了不同的取代基和不同的位置在决定镍催化剂性能方面都起着重要的作用。这为高性能聚合催化剂的未来设计提供了另一种策略。

更新日期：2021-02-07

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