Highly linear polyethylenes tailored with 2,6-bis[1-(p-dibenzo-cycloheptylarylimino)ethyl]pyridylcobalt dichlorides
| Autor: | Tongling Liang, Wen-Hua Sun, Yanping Ma, Liwei Guo, Arumugam Vignesh, Muhammad Zada, Dongzhi Zhu, Wenjuan Zhang |
|---|---|
| Rok vydání: | 2019 |
| Předmět: |
chemistry.chemical_classification
010405 organic chemistry Methylaluminoxane chemistry.chemical_element Crystal structure Polymer Polyethylene 010402 general chemistry 01 natural sciences 0104 chemical sciences Inorganic Chemistry End-group chemistry.chemical_compound chemistry Polymer chemistry Proton NMR Cobalt Isopropyl |
| Zdroj: | Dalton Transactions. 48:5604-5613 |
| ISSN: | 1477-9234 1477-9226 |
| DOI: | 10.1039/c9dt01109a |
| Popis: | A novel family of 2,6-bis[1-(p-dibenzocycloheptylarylimino)ethyl]pyridylcobalt dichlorides Co1-Co4 were synthesized and fully characterized by FT-IR, 1H NMR, and elemental analysis as well as X-ray diffraction analysis. The 1H NMR spectra of these paramagnetic cobalt complexes Co1-Co3 showed similar spectra with one set of signals, while Co4 possessed two sets of signals due to the different conformations caused by different substituents on the ortho-position of the N-aryl group. Crystal structures of Co1, Co2 and Co4 revealed similar square-pyrimidal geometry around the cobalt ion, in which two dibenzocycloheptyl groups adapted as cis-conformers, whereas Co3 possessed bistrigonal geometry and the two dibenzocycloheptyl groups were adapted as trans-conformers. On activation with methylaluminoxane (MAO) or modified MAO (MMAO), all these cobalt complexes displayed high catalytic activities towards ethylene polymerization (up to 1.21 × 107 g (PE) mol-1 (Co) h-1) and produced polyethylenes with narrow molecular distributions (PDI ≈ 2.0). Co3 bearing bulkier isopropyl substituents on the ortho-position gave much higher molecular weight of resultant polyethylene than the other cobalt complexes reported herein. The microstructure analysis of the PEs demonstrated that they are highly linear and contain a vinyl end group as the major group and saturated methyl as the minor group, in which the content of the unsaturated polymer chain relied on the ortho-substituent of the N-aryl group. |
| Databáze: | OpenAIRE |
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