A series of nickel complexes {NOONR}Ni（A： R=Me; B： R=t-Bu; C： R=OMe） based on salicylalde- hyde-imine ligands was synthesized through Schiff base condensation and metal complexation reaction. Upon activation with...A series of nickel complexes {NOONR}Ni（A： R=Me; B： R=t-Bu; C： R=OMe） based on salicylalde- hyde-imine ligands was synthesized through Schiff base condensation and metal complexation reaction. Upon activation with methylalurninoxane（MAO）, nickel complexes A--C all exhibited good catalytic activity[turnover frequency=5.2×10^5-16.3×10^5 g/（mol Ni-h）] and oligomer selectivity（above 85%, mass fraction） in ethylene oligomerization. In addition, C8--C12 olefins occupied an important proportion in the products of oligomers. Under the conditions of 4.0 MPa, 25℃ and A1/Ni molar ratio of 275, the catalytic selectivity of A/MAO system toward C8-C12 was about 30. 1%（mass fraction）, and the content of C8--C12 a-olefins was consistently above 70%. Furthermore, besides the ligand environment, the catalytic properties of A-C were substantially affected by experimental parameters, such as the reaction pressure, reaction temperature and A1/Ni ratio.展开更多
The discovery of highly active 2,6-bis（imino）pyridyl iron and cobalt complexes provided a milestone of latetransition metal catalysts for ethylene oligomerization and polymerization with being currently investigated...The discovery of highly active 2,6-bis（imino）pyridyl iron and cobalt complexes provided a milestone of latetransition metal catalysts for ethylene oligomerization and polymerization with being currently investigated for the scale-up process. The crucial problems are remaining in the catalytic systems： the catalytic systems targeting ethylene polymerization produce more oligomers at elevated reaction temperatures, however, there is a recognizable amount of high-molecularweight polyethylene remained in the modified catalytic system for the oligomerization process. Beyond the modification of bis（imino）pyridyl metal complexes, several alternative proeatalysts＇ models have been developed in our group. This review highlighted the achievements in exploring new iron and cobalt complexes with tridentate NNN ligands as procatalysts for ethylene oligomerization and polymerization.展开更多
A series of 2,6-bis（imino）pyridyl iron and cobalt complexes bearing p-substituent [2,6-（ArN=CMe）2C5H3N]- MCl2 （Ar=2,6-Me2C6H3, 2,4,6-Me3C6H2, 2,6-Me2-4-BrC6H2, 2,6-Me2-4-ClC6H2, 2,4-Me2-6-BrC6H2, 2,4-Me2-6- ClC6H...A series of 2,6-bis（imino）pyridyl iron and cobalt complexes bearing p-substituent [2,6-（ArN=CMe）2C5H3N]- MCl2 （Ar=2,6-Me2C6H3, 2,4,6-Me3C6H2, 2,6-Me2-4-BrC6H2, 2,6-Me2-4-ClC6H2, 2,4-Me2-6-BrC6H2, 2,4-Me2-6- ClC6H2, while M=Fe, Co） have been synthesized and investigated as catalysts for ethylene polymerization in the presence of modified methylaluminoxane as a cocatalyst. The electron effect and positions of the substituent of pyridinebisimine ligands were observed to affect considerably catalyst activity and polymer property.展开更多
The N,N -(phenyl-2-pyridinylmethylene)-3,3 ,5,5 -tetramethylbenzidine and its dimeric Co(Ⅱ)and Ni(Ⅱ) complexes were synthesized.The organic compound was characterized by elemental analyses,IR and NMR spectra,while t...The N,N -(phenyl-2-pyridinylmethylene)-3,3 ,5,5 -tetramethylbenzidine and its dimeric Co(Ⅱ)and Ni(Ⅱ) complexes were synthesized.The organic compound was characterized by elemental analyses,IR and NMR spectra,while the bimetal complexes were determined by elemental analyses,IR spectra as well as the single-crystal X-ray diffraction.The nickel complex showed high activity for ethylene polymerization and its cobalt analogue showed negligible active in ethylene activation.展开更多
Ethylene oligomerization has been investigated by using catalyst systemscomposed of nickel (II) diimine complexes (diimine = N, N′-o-phenylene bis(salicylideneaminato), N,N′-o-phenyl-enebisbenzal, N, N′-ethylenebis...Ethylene oligomerization has been investigated by using catalyst systemscomposed of nickel (II) diimine complexes (diimine = N, N′-o-phenylene bis(salicylideneaminato), N,N′-o-phenyl-enebisbenzal, N, N′-ethylenebisbenzal) and ethylaluminoxane (EAO). The main productsin toluene and at 110―200℃ were olefins with low carbon numbers (C_4―C_(10)). Effects of reactiontemperature, Al/Ni molar ratio and reaction period on both the catalytic activity and productdistribution were explored. The activity of 1.84 x 10~5 g of oligomer/(mol_(Ni)·h), with 87.4% ofselectivity to C_4―C_(10) olefins, was attained at 200℃ in the reaction when a catalyst composedof NiCl_2-(PhCH= o-NC_6H_4N= CHPh) and EAO was used.展开更多
Two new half-sandwich zirconium（IV） complexes bearing salicylaldimine ligands of the type Cp＊Zr[2-tBu-4-R-6-（CH=NiPr）C6H2O]C12[R=H（1）, tBu（2）] were prepared by the reaction of Cp＊ZrC13 with the corresponding...Two new half-sandwich zirconium（IV） complexes bearing salicylaldimine ligands of the type Cp＊Zr[2-tBu-4-R-6-（CH=NiPr）C6H2O]C12[R=H（1）, tBu（2）] were prepared by the reaction of Cp＊ZrC13 with the corresponding lithium of salicylaldimine ligands 2-tBu-4-R-6-（CH=NiPr）C6H2OLi[R=H（LiLa）, tBu（LiLb）]. Com- plexes 1 and 2 were characterized by 1H NMR, BC NMR spectroscopy and elemental analysis. When activated with AliBu3 and Ph3CB（C6F5）4, both complexes 1 and 2 exhibited reasonable catalytic activities for ethylene polymeriza- tion, producing polyethylenes with moderate molecular weight. Complexes 1 and 2 also exhibited reasonable catalyt- ic activities for ethylene copolymerization with 1-hexene, producing poly（ethylene-co-l-hexene）s with moderate molecular weight and reasonable 1-hexene content.展开更多
The unsymmetric precursor ethyl 6-acetylpyridine-2-carboxylate （4） was synthesized from 2,6-dimethylpyridine （1）. On the basis of this precursor, a new mono（imino）pyridine ligand （5） and the corresponding Co...The unsymmetric precursor ethyl 6-acetylpyridine-2-carboxylate （4） was synthesized from 2,6-dimethylpyridine （1）. On the basis of this precursor, a new mono（imino）pyridine ligand （5） and the corresponding Co（Ⅱ） complex {2-carbethoxy-6-[1-[（2,6-diethylphenyl）imino]ethyl]pyridine}CoCl2 （6） were prepared. The crystal structure of complex indicates that the 2-carbethoxy-6-iminopyridine is coordinated to the cobalt as a tridentate ligand using [N, N, O] atoms, and the coordination geometry of the central cobalt is a distorted trigonal bipyramid, with the pyridyl nitrogen atom and the two chlorine atoms forming the equatorial plane. Being applied to the ethylene oligomedzation, this cobalt complex shows catalytic activity of 1.820× 10^4 g/mol-Cooh at 101325 Pa of ethylene at 15.5℃ for 1 h, when 1000 equiv, of methylaluminoxane （MAO） is employed as the cocatalyst.展开更多
文摘A series of nickel complexes {NOONR}Ni（A： R=Me; B： R=t-Bu; C： R=OMe） based on salicylalde- hyde-imine ligands was synthesized through Schiff base condensation and metal complexation reaction. Upon activation with methylalurninoxane（MAO）, nickel complexes A--C all exhibited good catalytic activity[turnover frequency=5.2×10^5-16.3×10^5 g/（mol Ni-h）] and oligomer selectivity（above 85%, mass fraction） in ethylene oligomerization. In addition, C8--C12 olefins occupied an important proportion in the products of oligomers. Under the conditions of 4.0 MPa, 25℃ and A1/Ni molar ratio of 275, the catalytic selectivity of A/MAO system toward C8-C12 was about 30. 1%（mass fraction）, and the content of C8--C12 a-olefins was consistently above 70%. Furthermore, besides the ligand environment, the catalytic properties of A-C were substantially affected by experimental parameters, such as the reaction pressure, reaction temperature and A1/Ni ratio.
文摘The discovery of highly active 2,6-bis（imino）pyridyl iron and cobalt complexes provided a milestone of latetransition metal catalysts for ethylene oligomerization and polymerization with being currently investigated for the scale-up process. The crucial problems are remaining in the catalytic systems： the catalytic systems targeting ethylene polymerization produce more oligomers at elevated reaction temperatures, however, there is a recognizable amount of high-molecularweight polyethylene remained in the modified catalytic system for the oligomerization process. Beyond the modification of bis（imino）pyridyl metal complexes, several alternative proeatalysts＇ models have been developed in our group. This review highlighted the achievements in exploring new iron and cobalt complexes with tridentate NNN ligands as procatalysts for ethylene oligomerization and polymerization.
基金Project supported by the National Natural Science Foundationof China and China Petroleum ＆ Chemical Corporation （No. 20334030）.
文摘A series of 2,6-bis（imino）pyridyl iron and cobalt complexes bearing p-substituent [2,6-（ArN=CMe）2C5H3N]- MCl2 （Ar=2,6-Me2C6H3, 2,4,6-Me3C6H2, 2,6-Me2-4-BrC6H2, 2,6-Me2-4-ClC6H2, 2,4-Me2-6-BrC6H2, 2,4-Me2-6- ClC6H2, while M=Fe, Co） have been synthesized and investigated as catalysts for ethylene polymerization in the presence of modified methylaluminoxane as a cocatalyst. The electron effect and positions of the substituent of pyridinebisimine ligands were observed to affect considerably catalyst activity and polymer property.
文摘The N,N -(phenyl-2-pyridinylmethylene)-3,3 ,5,5 -tetramethylbenzidine and its dimeric Co(Ⅱ)and Ni(Ⅱ) complexes were synthesized.The organic compound was characterized by elemental analyses,IR and NMR spectra,while the bimetal complexes were determined by elemental analyses,IR spectra as well as the single-crystal X-ray diffraction.The nickel complex showed high activity for ethylene polymerization and its cobalt analogue showed negligible active in ethylene activation.
文摘Ethylene oligomerization has been investigated by using catalyst systemscomposed of nickel (II) diimine complexes (diimine = N, N′-o-phenylene bis(salicylideneaminato), N,N′-o-phenyl-enebisbenzal, N, N′-ethylenebisbenzal) and ethylaluminoxane (EAO). The main productsin toluene and at 110―200℃ were olefins with low carbon numbers (C_4―C_(10)). Effects of reactiontemperature, Al/Ni molar ratio and reaction period on both the catalytic activity and productdistribution were explored. The activity of 1.84 x 10~5 g of oligomer/(mol_(Ni)·h), with 87.4% ofselectivity to C_4―C_(10) olefins, was attained at 200℃ in the reaction when a catalyst composedof NiCl_2-(PhCH= o-NC_6H_4N= CHPh) and EAO was used.
基金Supported by the National Natural Science Foundation of China（No.21204082）.
文摘Two new half-sandwich zirconium（IV） complexes bearing salicylaldimine ligands of the type Cp＊Zr[2-tBu-4-R-6-（CH=NiPr）C6H2O]C12[R=H（1）, tBu（2）] were prepared by the reaction of Cp＊ZrC13 with the corresponding lithium of salicylaldimine ligands 2-tBu-4-R-6-（CH=NiPr）C6H2OLi[R=H（LiLa）, tBu（LiLb）]. Com- plexes 1 and 2 were characterized by 1H NMR, BC NMR spectroscopy and elemental analysis. When activated with AliBu3 and Ph3CB（C6F5）4, both complexes 1 and 2 exhibited reasonable catalytic activities for ethylene polymeriza- tion, producing polyethylenes with moderate molecular weight. Complexes 1 and 2 also exhibited reasonable catalyt- ic activities for ethylene copolymerization with 1-hexene, producing poly（ethylene-co-l-hexene）s with moderate molecular weight and reasonable 1-hexene content.
基金Project supported by the Program for Changjiang Scholars and Innovative Research Team in University, PCSIRT （No. IRT0559）, the National Natural Science Foundation of China （No. 20371039） and the Major State Basic Research Development Program （No. 2003CB214600）.
文摘The unsymmetric precursor ethyl 6-acetylpyridine-2-carboxylate （4） was synthesized from 2,6-dimethylpyridine （1）. On the basis of this precursor, a new mono（imino）pyridine ligand （5） and the corresponding Co（Ⅱ） complex {2-carbethoxy-6-[1-[（2,6-diethylphenyl）imino]ethyl]pyridine}CoCl2 （6） were prepared. The crystal structure of complex indicates that the 2-carbethoxy-6-iminopyridine is coordinated to the cobalt as a tridentate ligand using [N, N, O] atoms, and the coordination geometry of the central cobalt is a distorted trigonal bipyramid, with the pyridyl nitrogen atom and the two chlorine atoms forming the equatorial plane. Being applied to the ethylene oligomedzation, this cobalt complex shows catalytic activity of 1.820× 10^4 g/mol-Cooh at 101325 Pa of ethylene at 15.5℃ for 1 h, when 1000 equiv, of methylaluminoxane （MAO） is employed as the cocatalyst.
