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Efficient Suppression of Chain Transfer and Branching via C s ‐Type Shielding in a Neutral Nickel(II) Catalyst
Author(s) -
Wang Chaoqun,
Kang Xiaohui,
Dai Shengyu,
Cui Fengchao,
Li Yunqi,
Mu Hongliang,
Mecking Stefan,
Jian Zhongbao
Publication year - 2021
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.202013069
Subject(s) - electromagnetic shielding , branching (polymer chemistry) , catalysis , polymerization , nickel , aniline , polymer chemistry , aryl , chemistry , polar , materials science , chemical engineering , polymer , organic chemistry , physics , composite material , alkyl , astronomy , engineering
An effective shielding of both apical positions of a neutral Ni II active site is achieved by dibenzosuberyl groups, both attached via the same donors’ N ‐aryl group in a C s ‐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 6 g mol −1 ) are accessible, with a strictly linear microstructure (<0.1 branches/1000C). Key features of this highly active (4.3×10 5 turnovers h −1 ) 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.