Enhancing Thermal Stability and Living Fashion in α‑Diimine–Nickel-Catalyzed (Co)polymerization of Ethylene and Polar Monomer by Increasing the Steric Bulk of Ligand Backbone

Development of thermally stable nickel-based catalysts is highly desirable for industrial gas-phase olefin polymerizations. On the basis of the strategy of promoting the thermostability of nickel catalyst by the ligand backbone, we herein reported novel dibenzobarrelene-derived α-diimine nickel precatalysts for ethylene polymerization. Increasing the steric bulk on the ligand backbone was expected to inhibit the N-aryl rotation of the α-diimine ligands by the repulsive interactions, thus enhancing thermal stability (100 °C) and living fashion a temperatures up to 80 °C. Bulk ligand backbone also improved tolerance of nickel catalyst toward polar groups, and the α-diimine nickel catalyst containing a 2,6-tBu-dibenzobarrelene backbone catalyzed living copolymerization of ethylene and methyl 10-undecenoate.

开发热稳定型镍基催化剂是工业气相烯烃聚合领域的迫切需求。基于通过配体骨架提升镍催化剂热稳定性的策略，本文报道了一类新型二苯并桶烯（dibenzobarrelene）衍生的α-二亚胺（α-diimine）镍预催化剂，用于乙烯聚合反应。通过增大配体骨架的空间位阻，可借助排斥相互作用抑制α-二亚胺配体的N-芳基旋转，进而将催化剂热稳定性提升至100℃，并可在最高80℃的反应温度下实现活性聚合模式。增大的配体骨架空间位阻还可提升镍基催化剂对极性基团的耐受性，其中带有2,6-二叔丁基二苯并桶烯骨架的α-二亚胺镍催化剂可催化乙烯与10-十一烯酸甲酯的活性共聚反应。