Highly Linear Polyethylenes Achieved Using Thermo-Stable and Efficient Cobalt Precatalysts Bearing Carbocyclic-Fused NNN-Pincer Ligand

Highly Linear Polyethylenes Achieved Using Thermo-Stable and Efficient Cobalt Precatalysts Bearing Carbocyclic-Fused NNN-Pincer Ligand Full article

Journal

Molecules
, E-ISSN: 1420-3049

Output data

Year: 2019, Volume: 24, Number: 6, Article number : 1176, Pages count : DOI: 10.3390/molecules24061176

Tags

highly linear polyethylene; vinyl-end polyethylene; cobalt precatalyst; thermo-stable and efficient catalysis; correlation between structure and activity

Authors

Guo Jingjing ^1,2,3 , Wang Zheng ^2,3 , Zhang Wenjuan ¹ , Oleynik Ivan I. ⁴ , Vignesh Arumugam ^2,3 , Oleynik Irina V. ⁴ , Hu Xinquan ⁵ , Sun Yang ^2,3 , Sun Wen-Hua ^2,3

Affiliations

1	(Данные Web of science) Beijing Inst Fash Technol, Sch Mat Sci & Engn, Beijing Engn Res Ctr Text Nanofiber, Beijing Key Lab Clothing Mat R&D & Assessment, Beijing 100029, Peoples R China
2	(Данные Web of science) Chinese Acad Sci, Inst Chem, Key Lab Engn Plast, Beijing 100190, Peoples R China
3	(Данные Web of science) Chinese Acad Sci, Inst Chem, Beijing Natl Lab Mol Sci, Beijing 100190, Peoples R China
4	(Данные Web of science) NN Vorozhtsov Novosibirsk Inst Organ Chem, Pr Lavrentjeva 9, Novosibirsk 630090, Russia
5	(Данные Web of science) Zhejiang Univ Technol, Coll Chem Engn, Hangzhou 310014, Zhejiang, Peoples R China

Six examples of 2-(1-arylimino)ethyl-9-arylimino-5,6,7,8-tetrahydrocycloheptapyridine-cobalt(II) chloride complexes, [2-(1-ArN)C2H3-9-ArN-5,6,7,8-C5H8C5H3N]CoCl2, (Ar = 2-(C5H9)-6-MeC6H3 Co1, 2-(C6H11)-6-MeC6H3 Co2, 2-(C8H15)-6-MeC6H3 Co3, 2-(C5H9)-4,6-Me2C6H2 Co4, 2-(C6H11)-4,6-Me2C6H2 Co5, and 2-(C8H15)-4,6-Me2C6H2 Co6), were synthesized by the direct reaction of the corresponding ortho-cycloalkyl substituted carbocyclic-fused bis(arylimino)pyridines (L1-L6) and cobalt(II) chloride in ethanol with good yields. All the synthesized ligands (L1-L6) and their corresponding cobalt complexes (Co1-Co6) were fully characterized by FT-IR, H-1/C-13-NMR spectroscopy and elemental analysis. The crystal structure of Co2 and Co3 revealed that the ring puckering of both the ortho-cyclohexyl/cyclooctyl substituents and the one pyridine-fused seven-membered ring; a square-based pyramidal geometry is conferred around the metal center. On treatment with either methylaluminoxane (MAO) or modified methylaluminoxane (MMAO), all the six complexes showed high activities (up to 4.09 x 10(6) g of PE mol(-1) (Co) h(-1)) toward ethylene polymerization at temperatures between 20 degrees C and 70 degrees C with the catalytic activities correlating with the type of ortho-cycloalkyl substituent: Cyclopentyl (Co1 and Co4) > cyclohexyl (Co2 and Co5) > cyclooctyl (Co3 and Co6) for either R = H or Me and afforded strictly linear polyethylene (T-m > 130 degrees C). The narrow unimodal distributions of the resulting polymers are consistent with single-site active species for the precatalyst. Furthermore, compared to the previously reported cobalt analogues, the titled precatalysts exhibited good thermo-stability (up to 70 degrees C) and possessed longer lifetime along with a higher molecular weight of PE (M-w: 9.2 similar to 25.3 kg mol(-1)).

Guo J. , Wang Z. , Zhang W. , Oleynik I.I. , Vignesh A. , Oleynik I.V. , Hu X. , Sun Y. , Sun W-H.
Highly Linear Polyethylenes Achieved Using Thermo-Stable and Efficient Cobalt Precatalysts Bearing Carbocyclic-Fused NNN-Pincer Ligand

Molecules. 2019. V.24. N6. 1176 . DOI: 10.3390/molecules24061176 WOS Scopus РИНЦ

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Published online:

Mar 25, 2019

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