Chromium(III) complexes bearing 2-benzoxazolyl-6-arylimino-pyridines: Synthesis and their ethylene reactivity

Gao, Rong; Liang, Tongling; Sun, Wen‐Hua

doi:10.1016/j.jorganchem.2009.07.039

Cited by 39 publications

(26 citation statements)

References 64 publications

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“…Substituent groups and different hetero-atoms in the frameworks of ligands will significantly affect the catalytic activities. It is observed that the catalytic activities of NZN ligated catalysts strictly follow the trend NON > NNN > NSN [15].…”

Section: Nzn Ligands (Z = N O S)mentioning

confidence: 92%

“…Another kind of NNN ligated chromium catalyst was reported by Gao et al [15]. As is shown in the Fig.…”

Section: Nnn Ligandsmentioning

confidence: 95%

“…Upon activation with MAO (methylaluminoxane), these catalytic systems can trimerize ethylene to 1-hexene with unprecedented selectivity and productivity. NZN ligands (multidentate nitrogen-, oxygen-, or sulfur-bridged bis(imino) ligands [14,15], with some exceptions [16]), PNP ligands (chelating nitrogen-bridged diphosphine ligands) [17,18] and SNS ligands (chelating nitrogen-bridged disulfur ligands) [17,19] are the three different kinds of mixed-donor ligands investigated most for ethylene oligomerization.…”

Section: Synthesis and Properties Of Chromium-based Catalysts With DImentioning

confidence: 99%

“…Chromium complexes bearing NNN ligands exhibited high catalytic activities in ethylene oligomerization and polymerization [15,21,22]. It is reported that chromium complexes ligated by NNN species such as bis(imino)pyridine, (2-pyridylmethyl)amines, β-diketimate and pyrrolide-imine ligands can polymerize or oligomerize ethylene with great activity [21,[23][24][25].…”

Section: Nnn Ligandsmentioning

confidence: 99%

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Recent Research Progress in Preparation of Ethylene Oligomers with Chromium-Based Catalytic Systems

Zhu

Wang

2011

Designed Monomers and Polymers

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Ethylene oligomers, notably 1-hexene and 1-octene, are usually used as co-monomers in the production of linear low-density polyethylene (LLDPE). Because of the great value of 1-hexene and 1-octene, there have been many reports on the selective oligomerization of ethylene to 1-hexene and 1-octene recently. Research of ethylene oligomerization focuses mainly on the synthesis of catalysts and the mechanism of oligomerization. Much of this research concerns investigation into a catalytic system that can oligomerize ethylene to 1-hexene or 1-octene with high selectivity and activity. Different kinds of catalysts have been synthesized to catalyze the reactions, and the chromium-based homogeneous catalysts are found to be the most suitable ones. This article reviews the recent research progress in synthesis of chromium catalyst systems and study on the mechanism of ethylene oligomerization catalyzed by these catalysts.

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Section: Nzn Ligands (Z = N O S)mentioning

confidence: 92%

“…Another kind of NNN ligated chromium catalyst was reported by Gao et al [15]. As is shown in the Fig.…”

Section: Nnn Ligandsmentioning

confidence: 95%

Section: Synthesis and Properties Of Chromium-based Catalysts With DImentioning

confidence: 99%

Section: Nnn Ligandsmentioning

confidence: 99%

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Recent Research Progress in Preparation of Ethylene Oligomers with Chromium-Based Catalytic Systems

Zhu

Wang

2011

Designed Monomers and Polymers

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“…In recent years there has been a substantial acceleration in research activity concerned with homogeneous transition metal catalysts for ethylene oligomerization and polymerization. Chromium catalysts play an important role in both of these processes [1][2][3][4][5][6][7][8]. Since the first report of ethylene tetramerization to form 1-octene using Cr-bis(diphenylphosphino)amine (PNP) catalysts [9], numerous studies have investigated the relationship between ligand structure and catalytic properties.…”

mentioning

confidence: 99%

Ethylene tetramerization with a highly active and long-lifetime trinuclear diphenylphosphinoamine/Cr(III)/MAO catalyst

et al. 2012

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The synthesis and characterization of a novel trinuclear diphosphinoamine ligand 2 are reported. The ligand combined with Cr(III), activated with methylaluminoxane, lead to highly active and long-lifetime catalytic systems for the tetramerization of ethylene to form 1-octene. The effects of reaction temperature, reaction pressure, molar ratio of Al/Cr and bis(diphenylphosphino)amine/Cr on the catalytic activity and product selectivity were studied. Compared with its mononuclear analogue 1, ligand 2 showed a higher catalytic activity and longer lifetime for ethylene tetramerization in the presence of methylaluminoxane as cocatalyst. High molecular weight polyethylene was generated as a by-product with extremely broad molecular weight distributions. In recent years there has been a substantial acceleration in research activity concerned with homogeneous transition metal catalysts for ethylene oligomerization and polymerization. Chromium catalysts play an important role in both of these processes [1][2][3][4][5][6][7][8]. Since the first report of ethylene tetramerization to form 1-octene using Cr-bis(diphenylphosphino)amine (PNP) catalysts [9], numerous studies have investigated the relationship between ligand structure and catalytic properties. We were attracted by the potential for using chromium as an ethylene tetramerization active center because of its high catalytic activity and high selectivity to 1-octene. Here, we describe a new trinuclear PNP ligand that displays higher activity and a long lifetime for ethylene tetramerization to 1-octene.

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The chloro‐substituent enhances performance of 2,4‐bis (imino)pyridylchromium catalysts yielding highly linear polyethylene

Gansukh

Zhang

Flisak

et al. 2020

Applied Organom Chemis

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The five unsymmetrical 2‐[1‐(2,4‐dibenzhydryl‐6‐chlorophenylimino)ethyl]‐6‐[1‐(arylimino)ethyl]pyridine compounds (aryl: 2,6‐Me2Ph L1, 2,6‐Et2Ph L2, 2,6‐iPr2Ph L3, 2,4,6‐Me3Ph L4 and 2,6‐Et2–4‐MePh L5) were prepared and characterized with FT‐IR and 1H/13C NMR spectroscopy as well as elemental analysis. The treatment of L1 – L5 with CrCl3·3THF affords the corresponding chromium chloride complexes (Cr1 – Cr5) in excellent yields. The molecular structures of Cr2 and Cr3 characterized by X‐ray diffraction show a distorted octahedral geometry with three nitrogen atoms and three chlorine atoms around the metal center. On activation with either MAO or MMAO, Cr1 – Cr5 collectively display high activity (up to 14.96 × 106 g (PE) mol−1 (Cr) h−1 at 60 °C) affording highly linear polyethylene with low molecular weight distribution (Mw/Mn) ranging from 1.06 to 2.81. An in‐depth catalytic evaluation of Cr1 was conducted in order to investigate how the cocatalyst type and its amount, reaction temperature and polymerization time affect the catalytic activities and polymer properties.

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Chromium(III) complexes bearing 2-benzoxazolyl-6-arylimino-pyridines: Synthesis and their ethylene reactivity

Cited by 39 publications

References 64 publications

Recent Research Progress in Preparation of Ethylene Oligomers with Chromium-Based Catalytic Systems

Recent Research Progress in Preparation of Ethylene Oligomers with Chromium-Based Catalytic Systems

Ethylene tetramerization with a highly active and long-lifetime trinuclear diphenylphosphinoamine/Cr(III)/MAO catalyst

The chloro‐substituent enhances performance of 2,4‐bis (imino)pyridylchromium catalysts yielding highly linear polyethylene

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