Concerted steric and electronic effects on α-diimine nickel- and palladium-catalyzed ethylene polymerization and copolymerization

Qasim Muhammad; Chen Tan; Changle Chen

doi:10.1016/j.scib.2019.11.019

Concerted steric and electronic effects on α-diimine nickel- and palladium-catalyzed ethylene polymerization and copolymerization

Sci Bull (Beijing). 2020 Feb 26;65(4):300-307. doi: 10.1016/j.scib.2019.11.019. Epub 2019 Nov 18.

Authors

Qasim Muhammad¹, Chen Tan², Changle Chen³

Affiliations

¹ Key Laboratory of Soft Matter Chemistry, Department of Polymer Science and Engineering, University of Science and Technology of China, Hefei 230026, China.
² Institutes of Physical Science and Information Technology, Anhui University, Hefei 230601, China.
³ Key Laboratory of Soft Matter Chemistry, Department of Polymer Science and Engineering, University of Science and Technology of China, Hefei 230026, China. Electronic address: chengle@ustc.edu.cn.

PMID: 36659095
DOI: 10.1016/j.scib.2019.11.019

Abstract

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.

Keywords: Electronic effect; Nickel; Olefin polymerization; Palladium; Steric effect.