Vinyl-type polymerization of norbornene has been carried out with half-titanocene/MAO catalysts. It was found that the Cp（cyclopentadienyl）-bearing titanocene catalysts afford the polynorbornene at much higher yield...Vinyl-type polymerization of norbornene has been carried out with half-titanocene/MAO catalysts. It was found that the Cp（cyclopentadienyl）-bearing titanocene catalysts afford the polynorbornene at much higher yield than the related Cppentamethylcyclopentadienyl-bearing one. On the other hand, substitution of —OR ligand for chlorine at the Cp-bearing compound causes remarkbaly increase in catalytic activity. The optimum temperature for the polymerization is 60 ℃. All the polynorbornenes obtained with CpTi（OCH2Ph）3/MAO catalyst are soluble in the organic solvents such as cyclohexane and monochlorobenzene. The FTIR and 13C NMR spectra indicate that the polynorbornene obtained is vinyl-type polymer and has low stereo-regularity.展开更多
A series of nickel complexes{4 a:[(2,6-iPr2C6H3)N=CHC16H12O]Ni(Me)(Py),4b:[(2,6-iPr2C6H2OCH3)N=CHC16H12O]-Ni(Me)(Py),4 c:[(2,6-iPr2C6H2Cl)N=CHC16H12O]Ni(Me)(Py),and 4d:[(2,6-iPr2C6H2CF3)N=CHC16H12O]Ni(Me)(Py)}based on...A series of nickel complexes{4 a:[(2,6-iPr2C6H3)N=CHC16H12O]Ni(Me)(Py),4b:[(2,6-iPr2C6H2OCH3)N=CHC16H12O]-Ni(Me)(Py),4 c:[(2,6-iPr2C6H2Cl)N=CHC16H12O]Ni(Me)(Py),and 4d:[(2,6-iPr2C6H2CF3)N=CHC16H12O]Ni(Me)(Py)}based onβ-ketiminato ligands bearing various electron-donating or electron-withdrawing substituents on the para-position of the aniline group were synthesized and unambiguously characterized.The X-ray crystallographic analysis showed that complexes 4 b and 4 d adopted a nearsquare-planar geometry,and the anilines bearing a para-OMe or―CF3 group were found to situate on the axial position of the metal center.All complexes exhibited high activities up to 1.25×10^7–1.35×10^7 g PNB·molNi^–1·h^–1 toward norbornene(NBE)addition polymerization(conversion>91.2%in 2 min)under low loading of B(C6F5)3(B/Ni=3)at 30°C,affording polymers with high molecular weight up to 2.54×10^6–3.18×10^6.Different levels of decrease in catalytic activities could be observed for all catalysts as the reaction temperature increased;4 d bearing a strong electron-withdrawing―CF3 group showed the highest activity at 70°C,while others exhibited notable decrease in catalytic activity with the raise in reaction temperature.Complexes 4 a–4 d showed remarkable tolerance to polar groups and could efficiently promote the copolymerization of NBE with its polar derivatives,including NBE bearing small acetate and hydroxyl group,as well as bulky oligomers,yielding copolymers with high functional NBE incorporations.Novel NBE copolymers with high functional comonomer incorporations and improved solubility were obtained in high yields.展开更多
文摘Vinyl-type polymerization of norbornene has been carried out with half-titanocene/MAO catalysts. It was found that the Cp（cyclopentadienyl）-bearing titanocene catalysts afford the polynorbornene at much higher yield than the related Cppentamethylcyclopentadienyl-bearing one. On the other hand, substitution of —OR ligand for chlorine at the Cp-bearing compound causes remarkbaly increase in catalytic activity. The optimum temperature for the polymerization is 60 ℃. All the polynorbornenes obtained with CpTi（OCH2Ph）3/MAO catalyst are soluble in the organic solvents such as cyclohexane and monochlorobenzene. The FTIR and 13C NMR spectra indicate that the polynorbornene obtained is vinyl-type polymer and has low stereo-regularity.
基金financially supported by the National Natural Science Foundation of China (Nos. 21574097 and 21690071)
文摘A series of nickel complexes{4 a:[(2,6-iPr2C6H3)N=CHC16H12O]Ni(Me)(Py),4b:[(2,6-iPr2C6H2OCH3)N=CHC16H12O]-Ni(Me)(Py),4 c:[(2,6-iPr2C6H2Cl)N=CHC16H12O]Ni(Me)(Py),and 4d:[(2,6-iPr2C6H2CF3)N=CHC16H12O]Ni(Me)(Py)}based onβ-ketiminato ligands bearing various electron-donating or electron-withdrawing substituents on the para-position of the aniline group were synthesized and unambiguously characterized.The X-ray crystallographic analysis showed that complexes 4 b and 4 d adopted a nearsquare-planar geometry,and the anilines bearing a para-OMe or―CF3 group were found to situate on the axial position of the metal center.All complexes exhibited high activities up to 1.25×10^7–1.35×10^7 g PNB·molNi^–1·h^–1 toward norbornene(NBE)addition polymerization(conversion>91.2%in 2 min)under low loading of B(C6F5)3(B/Ni=3)at 30°C,affording polymers with high molecular weight up to 2.54×10^6–3.18×10^6.Different levels of decrease in catalytic activities could be observed for all catalysts as the reaction temperature increased;4 d bearing a strong electron-withdrawing―CF3 group showed the highest activity at 70°C,while others exhibited notable decrease in catalytic activity with the raise in reaction temperature.Complexes 4 a–4 d showed remarkable tolerance to polar groups and could efficiently promote the copolymerization of NBE with its polar derivatives,including NBE bearing small acetate and hydroxyl group,as well as bulky oligomers,yielding copolymers with high functional NBE incorporations.Novel NBE copolymers with high functional comonomer incorporations and improved solubility were obtained in high yields.
