Concerted effect of steric and electronic substituents is a powerful strategy to enhance the catalytic performance of α-diiminonickel precatalysts for ethylene polymerization, but less investigated so far. In this study, the synthesis of a series of unsymmetrical α-diiminonickel complexes, featuring the sterically crowded 2,6-dibenzhydryl-3,4,5-trimethoxyphenylimine and 2,4,6-(alkyl)phenylimine units, is described. Some of these complexes, including ligand and abnormal organic compound are presented in X-ray structures. All the nickel complexes, extensively studied with two alkylating reagents (Me₂AlCl and MMAO), demonstrated excellent catalytic performance, with activity level in the range of 10⁶–10⁷ g mol⁻¹ h⁻¹ across a broad temperature range (30 °C–90 °C). Of significant note, concerted effect of three OMe substituents and two benzhydryl groups present at the same imine unit, significantly improved chain propagation and thereby facilitated the synthesis of ultra-high molecular weight (up to 1.2 × 10⁶ g mol⁻¹) polyethylene with high branching degree (up to 205/1000C) and narrow polymer molecular weight distributions (Ð = < 1.80). Moreover, the obtained polyethylene, especially the ultra-high MW samples, exhibited excellent material properties (up to σ_b = 7.58 MPa with ε_b = 1025 % and E = 5.32 MPa), along with elastic recovery rates of 59–65 %. These properties of obtained polyethylene highlight characteristics of typical thermoplastic polyolefin elastomers.

空间和电子取代基的协同作用是增强α-二亚胺镍预催化剂乙烯聚合催化性能的有效策略，但迄今为止研究较少。在这项研究中，描述了一系列不对称α-二亚胺镍配合物的合成，其特征是空间拥挤的2,6-二苯甲基-3,4,5-三甲氧基苯亚胺和2,4,6-(烷基)苯亚胺单元。其中一些配合物，包括配体和异常有机化合物，以 X 射线结构呈现。使用两种烷基化试剂（Me ₂ AlCl 和MMAO）对所有镍^{配合物进行了}广泛研究，显示出优异的催化性能，在^较宽的温度 范围（30 °C–90 °C）。值得注意的是，同一亚胺单元上存在的三个OMe取代基和两个二苯甲基的协同作用，显着改善了链增长，从而促进了超高分子量（高达1.2×10 ⁶  g mol ^-1 ）聚乙烯的合成高支化度（高达 205/1000C）和窄聚合物分子量分布（ Ð = < 1.80）。此外，所获得的聚乙烯，特别是超高分子量样品，表现出优异的材料性能（高达σ _b  = 7.58 MPa，ε _b  = 1025 % 和 E = 5.32 MPa），以及 59-65 % 的弹性恢复率。所得聚乙烯的这些性能突出了典型热塑性聚烯烃弹性体的特性。