Wang Chaoqun, Kang Xiaohui, Dai Shengyu, Cui Fengchao, Li Yunqi, Mu Hongliang, Mecking Stefan, Jian Zhongbao
State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Renmin Street 5625, Changchun, 130022, China.
University of Science and Technology of China, Hefei, 230026, China.
Angew Chem Int Ed Engl. 2021 Feb 19;60(8):4018-4022. doi: 10.1002/anie.202013069. Epub 2020 Dec 23.
An effective shielding of both apical positions of a neutral Ni active site is achieved by dibenzosuberyl groups, both attached via the same donors' N-aryl group in a C -type arrangement. The key aniline building block is accessible in a single step from commercially available dibenzosuberol. This shielding approach suppresses chain transfer and branch formation to such an extent that ultrahigh molecular weight polyethylenes (5×10 g mol ) are accessible, with a strictly linear microstructure (<0.1 branches/1000C). Key features of this highly active (4.3×10 turnovers h ) catalyst are an exceptionally facile preparation, thermal robustness (up to 90 °C polymerization temperature), ability for living polymerization and compatibility with THF as a polar reaction medium.
通过二苯并亚芴基实现了对中性镍活性位点两个顶端位置的有效屏蔽，二者均通过相同供体的N -芳基以C型排列连接。关键的苯胺结构单元可从市售的二苯并亚芴醇一步制得。这种屏蔽方法极大地抑制了链转移和支化形成，从而能够得到超高分子量聚乙烯（5×10⁶ g·mol⁻¹），且具有严格的线性微观结构（<0.1个支链/1000个C）。这种高活性（4.3×10⁶ 次周转/h）催化剂的关键特性包括制备极其简便、热稳定性强（聚合温度高达90°C）、具有活性聚合能力以及与作为极性反应介质的四氢呋喃具有相容性。
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