0000000001305052
AUTHOR
Wen-hua Sun
showing 40 related works from this author
Constrained formation of 2-(1-(arylimino)ethyl)-7-arylimino-6,6-dimethylcyclopentapyridines and their cobalt(ii) chloride complexes: synthesis, chara…
2015
A series of 2-(1-(arylimino)ethyl)-7-arylimino-6,6-dimethylcyclopentapyridine derivatives (L1-L5) was synthesized, and individually reacted with cobalt(II) chloride to form the corresponding cobalt chloride complexes (C1-C4). These compounds were characterized, and the single crystal X-ray diffraction for two representative cobalt complexes was carried out. The molecular structures indicate that 2,7-bis(arylimino)cyclopentapyridines act as tridentate ligands; however, one of the Co-N coordinative bonds is weak due to the spatial separation of nitrogen atoms. Upon activation with either MAO or MMAO, all cobalt complexes exhibit catalytic activities toward ethylene. Polymerization takes place…
Dinuclear chloroneodymium quinolinylcarboxylates: The molecular structures affected by water and the catalytic behavior toward isoprene polymerization
2016
Abstract A series of dinuclear chloroneodymium quinolinylcarboxylate compounds was synthesized and characterized. The nature and importance of metal-organic aggregations have been considered as an important factor regarding the molecular structure and catalytic performance. The neodymium center in all the title compounds exhibits the coordination numbers of 8. Cage aggregation was observed in the solid state, and the cyclic arrangement was achieved when water molecules were incorporated into the structure. Upon the activation with Al(i-Bu)3, all the title neodymium compounds form the efficient catalysts for isoprene polymerization. The catalytic activities are not strongly affected by the m…
Ethylene polymerization by the thermally unique 1-[2-(bis(4-fluoro phenyl)methyl)-4,6- dimethylphenylimino]-2-aryliminoacenaphthylnickel precursors
2015
A series of 1-[2-(bis(4-fluorophenyl)methyl)-4,6-dimethylphenylimino]-2-aryliminoacenaphthylene derivatives together with the corresponding nickel bromide complexes was synthesized and characterized. Representative complexes C2 and C5 were characterized by the single-crystal X-ray diffraction, revealing a distorted tetrahedral geometry. Upon activation with either methylaluminoxane (MAO) or ethylaluminum sesquichloride (EASC), all nickel complexes exhibited high activities towards ethylene polymerization, producing polyethylene with a relatively low degree of branching and narrow polydispersity. Complex C1 maintained good activity at elevated reaction temperatures, which indicates significa…
Propyl substituted 4-arylimino-1,2,3-trihydroacridylnickel complexes: Their synthesis, characterization and catalytic behavior toward ethylene
2015
Propyl substituted 4-arylimino-1,2,3-trihydroacridylnickel dihalide complexes were designed and prepared by metal-induced template reaction with NiCl2 center dot 6H(2)O or (DME)NiBr2. They were characterized by infrared spectroscopy and elemental analysis. Single crystal X-ray crystallography of representative complex Ni3 revealed a distorted trigonal bipyramidal geometry around nickel. The catalytic activities of the title nickel complexes were negatively affected by propyl substituent on their backbone when comparing with the results by unsubstituted ones. With the activation of diethylaluminium chloride, all nickel complexes exhibited moderate activity (up to 5.10 x 10(5) g mol(-1)(Ni) h…
Enhancing performance of α‐diiminonickel precatalyst for ethylene polymerization by substitution with the 2,4‐bis(4,4'‐dimethoxybenzhydryl)‐6‐methylp…
2020
High activities in ethylene polymerization predetermine α‐diiminonickel precatalysts for potential industrial applications. In our study, we have synthesized and characterized a series of unsymmetrical 1‐(2,4‐bis(4,4′‐dimethoxybenzhydryl)‐6‐MeC6H2N)‐2‐arylimino‐acenaphthylene nickel(II) halides. The single‐crystal X‐ray diffraction study of representative compounds reveals distorted tetrahedral geometry. On activation with either Me2AlCl or modified methylaluminoxane, these nickel complexes exhibit high activities of the order of 106 g of PE (mol of Ni)−1 h−1 and produce polyethylene of generic application characterized by high molecular weight, narrow molecular weight distribution, and mod…
A practical ethylene polymerization for vinyl-polyethylenes: synthesis, characterization and catalytic behavior of α,α’-bisimino-2,3:5,6- bis(pentame…
2016
A series of α,α′-bis(arylimino)-2,3:5,6-bis(pentamethylene)pyridyliron chlorides was synthesized in a one-pot reaction and characterized by FT-IR and elemental analysis as well as X-ray crystallography for one representative iron complex, where the Fe center adopts a distorted square pyramidal geometry with three coordinating nitrogen and two chlorine atoms. The iron precatalysts, upon treatment with either methylaluminoxane (MAO) or modified methylaluminoxane (MMAO), exhibit high activities in the range of 107 g of PE per mol of Fe per h toward ethylene polymerization, yielding highly linear and, more importantly, vinyl-polyethylenes. The correlation between the structural features of iron…
2-(1-Aryliminoethyl)-9-arylimino-5,6,7,8- tetrahydrocycloheptapyridyl iron(II) dichloride: synthesis, characterization, and the highly active and tun…
2014
A series of 2-(1-arylimino)ethyl-9-arylimino-5,6,7,8-tetrahydrocycloheptapyridine derivatives was synthesized and fully characterized, and thereafter reacted with iron dichloride to form their corresponding iron(II) complexes. The single crystals of representative organic and iron complex compounds were obtained and analyzed by the X-ray diffraction analysis, indicating the distorted bipyramidal geometry around the iron core. Moreover, DFT calculations were performed on selected species to determine their structural features. On treatment with either MAO or MMAO, all iron complex pre-catalysts showed high activities (up to 1.56 × 10(7) gPE mol(-1)(Fe) h(-1)) toward ethylene polymerization. …
The chloro‐substituent enhances performance of 2,4‐bis (imino)pyridylchromium catalysts yielding highly linear polyethylene
2020
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‐i Pr2Ph 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 hig…
Achieving branched polyethylene waxes by aryliminocycloocta[b]pyridylnickel precatalysts: Synthesis, characterization, and ethylene polymerization
2017
Cycloocta[b]pyridin-10-one was prepared to form the corresponding imino derivatives, which then reacted with (DME)NiBr2 to form 10-aryliminocycloocta[b]pyridylnickel bromides (Ni1–Ni5). The new compounds were characterized by means of FT-IR spectroscopy as well as elemental analysis and the organic ligands were also analyzed by the NMR measurements. Furthermore, the molecular structure of a representative complex Ni3 was determined by the single crystal X-ray diffraction, indicating the distorted tetrahedral geometry around the nickel atom. Upon the activation with either methylaluminoxane (MAO) or diethylaluminium chloride (Et2AlCl), the title nickel complexes exhibited high activity in et…
2-(N,N-Diethylaminomethyl)-6,7-trihydroquinolinyl-8-ylideneamine-Ni(ii) chlorides: application in ethylene dimerization and trimerization
2020
A series of Ni(II) complexes with the general formula [2-((NEt2)Me)-8-{N(Ar)}C9H8N]NiCl2, where Ar = 2,6-Me2C6H3 in Ni1, 2,6-Et2C6H3 in Ni2, 2,6-i-Pr2C6H3 in Ni3, 2,4,6-Me3C6H2 in Ni4, 2,6-Et2-4-MeC6H2 in Ni5, and 2,4,6-t-Bu3C6H2 in Ni6, has been prepared using a one-pot reaction of 2-(N,N-diethylaminomethyl)-6,7-dihydroquinolin-8(5H)-one with the corresponding aniline and nickel dichloride hexahydrate. The resultant complexes were characterized using elemental analysis and FT-IR spectroscopy, while the mononuclear Ni1 and Ni3 were also the subject of single-crystal X-ray diffraction study. On activation with MMAO, the complexes Ni1–Ni6 displayed good activity in ethylene oligomerization, f…
Ethylene oligomerization with 2-hydroxymethyl-5,6,7-trihydroquinolinyl-8-ylideneamine-Ni(II) chlorides
2021
Abstract A series of Ni complexes of the general formula [2-(MeOH)-8-{N(Ar)}C9H8N]NiCl2, where Ar = 2,6-Me2C6H3 in Ni1; 2,6-Et2C6H3 in Ni2; 2,6-i-Pr2C6H3 in Ni3; 2,4,6-Me3C6H2 in Ni4; 2,6-Et2-4-MeC6H2 in Ni5 and 2,4,6-t-Bu3C6H2 in Ni6 has been synthesized and characterized by elemental analysis and IR spectroscopy. On activation with MMAO or Et2AlCl, these complexes showed high activity in ethylene oligomerization, reaching 2.23 × 106 g·mol–1 (Ni) h–1 at 30 °C with the Al/Ni ratio of 5500 and 9.11 × 105 g·mol–1 (Ni) h–1 with the Al/Ni of 800, respectively. Moreover, the content of α-C4 indicated high selectivity exceeding 99% in the Ni/Et2AlCl system. Comparing with the previous report by o…
Activity and Thermal Stability of Cobalt(II)-Based Olefin Polymerization Catalysts Adorned with Sterically Hindered Dibenzocycloheptyl Groups.
2019
Five examples of unsymmetrical 2-(2,4-bis(dibenzocycloheptyl)-6-methylphenyl- imino)ethyl)-6-(1-(arylyimino)ethyl)pyridine derivatives (aryl = 2,6-Me2C6H3 in L1
Finely tuned nickel complexes as highly active catalysts affording branched polyethylene of high molecular weight: 1-(2,6-Dibenzhydryl-4- methoxyphen…
2018
Abstract A series of unsymmetrical 1,2-bis(imino)acenaphthenenickel(II) halides containing N-2,6-dibenzhydryl-4-methoxyphenyl – a single bulky group with adjusted electron donating properties – has been synthesized and characterized. These compounds adopt distorted tetrahedral geometry and their 1H NMR spectra show the paramagnetically shifted peaks. On activation with a low amount of Et2AlCl or ethylaluminum sesquichloride (EASC), these nickel complexes display high activity in ethylene polymerization, yielding the polyethylene of high molecular weight. They are also stable at elevated temperature; superb activity of 2.51 × 106 g of PE (mol of Ni)−1 h−1 can be attained at 90 °C. The result…
2-Chloro/phenyl-7-arylimino-6,6-dimethylcyclopenta[b]pyridylnickel chlorides: Synthesis, characterization and ethylene oligomerization
2017
Abstract 2-Chloro/phenyl-7-arylimino-6,6-dimethylcyclopenta[b]pyridylnickel chlorides (Ni1–Ni8) were synthesized from the respective ligands L1–L8 and characterized. Upon activation with either methylaluminoxane (MAO) or ethylaluminium sesquichloride (EASC), they show high catalytic activity of up to 10.84 × 106 g(oligomer) mol− 1(Ni) h− 1 in ethylene oligomerization. The products range from butenes to dodecenes for Ni1–Ni4, but are limited to butenes and hexenes in the case of Ni5–Ni8. DFT calculations indicate that the Ni C bond length in the model alkyl complexes depends both on the nature of the substituents at the heterocycles and the kind of the alkyl group, shedding some light on the…
Enhancing Performance of a Bis(arylimino)pyridine‐Iron Precatalyst for Ethylene Polymerization by Substitution with a 2,4‐Bis(4,4′‐dimethoxybenzhydry…
2021
A series of unsymmetrical 2-(2,4-bis(bis(4-methoxyphenyl)methyl)-6-MeC6H2N)-6-(1-(arylimino)ethyl)pyridine-iron halides has been synthesized and characterized. The molecular structure of two representative species was determined by the single-crystal X-ray diffraction. Activated with either MAO or MMAO, the precatalysts displayed high activity, reaching 2.19×107 g PE (mol Fe)−1 h−1 at 60 °C in ethylene polymerization. The microstructural analysis of the polymers obtained indicates highly linear polyethylene containing a vinyl chain end.
Progression of Diiminopyridines: From Single Application to Catalytic Versatility
2015
Diiminopyridyl metal complexes, first characterized several decades ago, found practical application in 1998 when they were used as precatalysts in coordinative ethylene polymerization. This discovery contributed to the so-called postmetallocene revolution and triggered the large-scale experimental and theoretical research aimed at understanding diversified diiminopyridine chemistry. The results of this quest, some of which were intriguing and difficult to anticipate, are discussed and summarized in the current Review.
Tailoring polymers through interplay of ligands within precatalysts: 8-(Nitro/benzhydryl-arylimino)-7,7-dimethyl-5,6-dihydroquinolylnickel halides in…
2017
A series of 8-(nitro/benzhydryl-substituted arylimino)-7,7-dimethyl-5,6-dihydroquinolines and the corresponding nickel halide complexes were synthesized and characterized. Molecular structures of representative nickel complexes were determined by single crystal X-ray diffraction, showing the dinuclear dimers with distorted square-pyramidal geometry around the nickel center. The binding energies determined by X-ray photoelectron spectroscopy (XPS) indicate the effective coordination between the sp2-nitrogen and nickel atoms as well as the influence of both the halogen ligands and the substituents within dihydroquinolines on the strength of the NiN bond. Ethylene polymerization with the nicke…
Nickel(II) complexes with sterically hindered 5,6,7-trihydroquinoline derivatives selectively dimerizing ethylene to 1-butene
2022
A series of nickel complexes bearing N,N-bidentate ligands has been synthesized and characterized by elemental analysis and infrared (IR) spectroscopy. High ethylene dimerization activity, reaching 2.43 × 106 g mol−1(Ni)h−1, was achieved by using these complexes as precatalysts activated with Me2AlCl. Moreover, the selectivity to obtain α-C4 was high (93%–96%). Comparing with the previous report by our group, the higher activity and selectivity may be attributed to the substituent at the 2-position within the ligand, creating the steric hindrance around the metal atom.
CCDC 1831144: Experimental Crystal Structure Determination
2018
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CCDC 1530049: Experimental Crystal Structure Determination
2017
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CCDC 1554541: Experimental Crystal Structure Determination
2018
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CCDC 1008609: Experimental Crystal Structure Determination
2014
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CCDC 1008610: Experimental Crystal Structure Determination
2014
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CCDC 1542647: Experimental Crystal Structure Determination
2017
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CCDC 1486040: Experimental Crystal Structure Determination
2016
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CCDC 1476785: Experimental Crystal Structure Determination
2016
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CCDC 1486038: Experimental Crystal Structure Determination
2016
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CCDC 1042277: Experimental Crystal Structure Determination
2015
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CCDC 1831143: Experimental Crystal Structure Determination
2018
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CCDC 1008608: Experimental Crystal Structure Determination
2014
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CCDC 2005997: Experimental Crystal Structure Determination
2020
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CCDC 1486039: Experimental Crystal Structure Determination
2016
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CCDC 1530048: Experimental Crystal Structure Determination
2017
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CCDC 1054235: Experimental Crystal Structure Determination
2015
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CCDC 1043484: Experimental Crystal Structure Determination
2015
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CCDC 1042276: Experimental Crystal Structure Determination
2015
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CCDC 1905876: Experimental Crystal Structure Determination
2019
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CCDC 1905877: Experimental Crystal Structure Determination
2019
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CCDC 2005998: Experimental Crystal Structure Determination
2020
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CCDC 1054234: Experimental Crystal Structure Determination
2015
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