In this work, we report a series of novel nickel(II) dibromide and dichloride complexes with 2-iminopyridine and 2-iminoquinoline ligands bearing electron-withdrawing substituents (F, Cl, CF₃), that have demonstrated high ethylene dimerization activity [up to 19.2 × 10⁶ g of oligomers·(mol Ni)⁻¹ h⁻¹] in the presence of MAO or Et₂AlCl, affording predominantly a mixture of 1-butene and cis- and trans-2-butene (C₄ selectivity varies from 89 to 100%; 2-butenes selectivity in the C₄ fraction approaches 96%). The effects of ligand substituents and the cocatalyst nature on the activity and selectivity of the nickel(II) complexes in ethylene dimerization have been established. Several nickel complexes were supported on silica-alumina and the resulting heterogeneous catalysts were probed towards ethylene dimerization. These catalysts also afford 2-butenes, with the activity and C₄ selectivity being comparable to that of homogeneous catalysts.

中文翻译：

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使用均相和负载型镍（II）2-亚氨基吡啶催化剂将乙烯选择性二聚为2-丁烯

在这项工作中，我们报告了一系列新型的二溴化镍（II）和二氯化物配合物，它们带有带有吸电子取代基（F，Cl，CF ₃）的2-亚氨基吡啶和2-亚氨基喹啉配体，它们具有很高的乙烯二聚活性。在MAO或Et ₂ AlCl存在下，生成19.2×10 ⁶  g的低聚物·（mol Ni）^-1  h ^-1 ] ，主要提供1-丁烯与顺式和反式-2-丁烯的混合物（C ₄选择性从89％到100％不等； C ₄中的2-丁烯选择性分数接近96％）。已经建立了配体取代基和助催化剂性质对乙烯二聚中镍（II）配合物的活性和选择性的影响。将几种镍配合物负载在二氧化硅-氧化铝上，并探索所得的非均相催化剂进行乙烯二聚。这些催化剂还提供了2-丁烯，其活性和C ₄选择性与均相催化剂相当。