Adjusting ortho-cycloalkyl ring size in a cycloheptyl-fused n,n,n-iron catalyst as means to control catalytic activity and polyethylene properties

Adjusting ortho-cycloalkyl ring size in a cycloheptyl-fused n,n,n-iron catalyst as means to control catalytic activity and polyethylene properties Full article

Journal

Catalysts
ISSN: 2073-4344

Output data

Year: 2020, Volume: 10, Number: 9, Article number : 1002, Pages count : 16 DOI: 10.3390/catal10091002

Tags

Ethylene polymerization; Fused bis(imino)pyridine; Iron(II) precatalysts; Ortho-benzhydryl; Ortho-cycloalkyl; Structure–activity correlation; Structure–molecular weight correlation

Authors

Han M. ^1,2 , Zhang Q. ^1,2 , Oleynik I.I. ³ , Suo H. ^1,2 , Oleynik I.V. ³ , Solan G.A. ^1,4 , Ma Y. ¹ , Liang T. ¹ , Sun W.-H. ^1,2,5

Affiliations

1	(Scopus) Key Laboratory of Engineering Plastics and Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, China
2	(Scopus) CAS Research/Education Center for Excellence in Molecular Sciences and International School, University of Chinese Academy of Sciences, Beijing, 100049, China
3	(Scopus) N.N. Vorozhtsov Novosibirsk Institute of Organic Chemistry, Pr. Lavrentjeva 9, Novosibirsk, 630090, Russian Federation
4	(Scopus) Department of Chemistry, University of Leicester, University Road, Leicester, LE1 7RH, United Kingdom
5	(Scopus) State Key Laboratory for Oxo Synthesis and Selective Oxidation, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou, 730000, China

Five examples of bis(arylimino)tetrahydrocyclohepta[b]pyridine dichloroiron(II) complex, [2-{(Ar)N=CMe}-9-{N(Ar)}C10 H10 N]FeCl2 (Ar = 2-(C5 H9)-4,6-(CHPh2)2 C6 H2 Fe1, 2-(C6 H11)-4,6-(CHPh2)2 C6 H2 Fe2, 2-(C8 H15)-4,6-(CHPh2)2 C6 H2 Fe3, 2-(C12 H23)-4,6-(CHPh2)2 C6 H2 Fe4, and 2,6-(C5 H9)2-4-(CHPh2)C6 H2 Fe5), incorporating ortho-pairings based on either benzhydryl/cycloalkyl (ring sizes ranging from 5 to 12) or cyclopentyl/cyclopentyl groups, have been prepared in reasonable yield by employing a simple one-pot template strategy. Each complex was characterized by FT-IR spectroscopy, elemental analysis, and for Fe3 and Fe5 by single crystal X-ray diffraction; pseudo-square pyramidal geometries are a feature of their coordination spheres. On treatment of Fe1–Fe5 with modified methylaluminoxane (MMAO) or methylaluminoxane (MAO), a range in catalytic activities for ethylene polymerization were observed with benzhydryl/cyclopentyl-containing Fe1/MMAO achieving the maximum level of 15.3 × 106 g PE mol−1 (Fe) h−1 at an operating temperature of 70◦ C. As a key trend, the activity was found to drop as the ortho-cycloalkyl ring size increased: Fe1C5H9/CHPh2 ~Fe5C5H9/C5H9 > Fe2C6H11/CHPh2 > Fe3C8H15/CHPh2 > Fe4C12H23/CHPh2. Furthermore, strictly linear polyethylenes (Tm > 126◦ C) were formed with molecular weights again dependent on the ortho-cycloalkyl ring size (up to 55.6 kg mol−1 for Fe1/MAO); narrow dispersities were a characteristic of all the polymers (Mw /Mn range: 2.3–4.7), highlighting the well-controlled nature of these polymerizations. © 2020 by the authors. Licensee MDPI, Basel, Switzerland.

Han M. , Zhang Q. , Oleynik I.I. , Suo H. , Oleynik I.V. , Solan G.A. , Ma Y. , Liang T. , Sun W.-H.
Adjusting ortho-cycloalkyl ring size in a cycloheptyl-fused n,n,n-iron catalyst as means to control catalytic activity and polyethylene properties

Catalysts. 2020. V.10. N9. 1002 :1-16. DOI: 10.3390/catal10091002 WOS Scopus РИНЦ

Full text from publisher

Published online:

Sep 2, 2020

Web of science	WOS:000582027600001
Scopus	2-s2.0-85090534344
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