α-Diimine nickel catalysts have attracted much attention in olefin polymerization over the past three decades, and the steric bulk strategy has become a common tool to regulate the related polymerization reactions. In contrast, the macrocyclic strategy is much less utilized in olefin polymerization due to the very difficult synthesis. In this contribution, a novel aza-cyclophane-based macrocyclic α-diimine nickel catalyst was synthesized via a simplified route with only 4 steps. Compared to the acyclic nickel analogue, this cyclic nickel pre-catalyst with the activation by a cocatalyst such as MAO or diethyl aluminum chloride (DEAC) exhibited remarkable advantages in ethylene polymerization including enhanced catalytic activity (9000 kg mol⁻¹ h⁻¹), superior thermostability (up to 130 °C), and notably higher polymer molecular weight (up to 29 times). Thus, ultrahigh molecular weight polyethylenes (UHMWPE: 1806 kDa) were produced by adjusting the cocatalyst and reaction solvent. This clearly indicated the effectiveness of the macrocyclic strategy. Notably, the use of a MgBu₂/DEAC binary cocatalyst enabled the formation of a heterogeneous solid-supported nickel catalytic system, further improving the catalytic activity and molecular weight in ethylene polymerization.

中文翻译：

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氮杂环芳负载大环α-二亚胺镍催化剂用于乙烯聚合

过去三十年来，α-二亚胺镍催化剂在烯烃聚合中备受关注，空间本体策略已成为调节相关聚合反应的常用工具。相比之下，由于合成非常困难，大环策略在烯烃聚合中的应用要少得多。在该贡献中，通过仅 4 个步骤的简化路线合成了一种新型的基于氮杂环芳的大环 α-二亚胺镍催化剂。与无环镍类似物相比，这种通过MAO或二乙基氯化铝（DEAC）等助催化剂活化的环状镍预催化剂在乙烯聚合中表现出显着的优势，包括增强的催化活性（9000 kg mol ^-1 h ^-1），优异的热稳定性（高达 130 °C），并且聚合物分子量显着更高（高达 29 倍）。因此，通过调整助催化剂和反应溶剂生产了超高分子量聚乙烯（UHMWPE：1806 kDa）。这清楚地表明了大周期策略的有效性。值得注意的是，MgBu ₂ /DEAC二元助催化剂的使用能够形成非均相固载镍催化体系，进一步提高了乙烯聚合中的催化活性和分子量。