For transition metal-based olefin polymerization catalysts, ligand steric and electronic effects can strongly influence important catalytic properties. However, the simultaneous tuning of both steric and electronic effects has not been explored in most of the previous studies. In this contribution, a strategy to tune the ligand electronic and steric effects in a concerted fashion is reported. In such a system, both dibenzhydryl groups and multiple methoxy/fluoro groups were installed in α-diimine ligands. In addition to strongly influencing ligand electronics, the methoxy/fluoro groups can interact with the dibenzhydryl groups and efficiently increase ligand sterics. In ethylene polymerization, this concurrent tuning of electronic and steric effects can lead to simultaneous enhancement of several parameters (activity, stability, polymer molecular weight, melting point, branching density) for both the nickel and palladium catalysts. The effectiveness of this strategy is highly attractive for future studies in other catalytic systems.

对于基于过渡金属的烯烃聚合催化剂，配体空间和电子效应可以强烈影响重要的催化性能。然而，在之前的大多数研究中都没有探索同时调整空间和电子效应。在这篇文章中，报告了一种以协调一致的方式调整配体电子和空间效应的策略。在这样的系统中，二苯甲基和多个甲氧基/氟基团都安装在 α-二亚胺配体中。除了强烈影响配体电子学之外，甲氧基/氟基团还可以与二苯甲基相互作用并有效地增加配体空间。在乙烯聚合中，电子和空间效应的这种同时调整可以导致几个参数（活性、稳定性、镍和钯催化剂的聚合物分子量、熔点、支化密度）。该策略的有效性对于其他催化系统的未来研究极具吸引力。