摘要
In order to study the influence of substituents on imino-aryl rings of mono(imino)pyrrole-transition metal complexes to their ethylene polymerization performance,a series of mono(imine)pyrroles(L1-L3)were synthesized by microwave irradiation from 2-acetylpyrrole and a series of 2,6-position disubstituted anilines(substituent:H,Me,Et).A simplified synthetic method was introduced to prepare the corresponding nickel complexes NiL2(1~3)with direct condensation of mono(imine)pyrrole ligands and nickel dichloride.All the compounds were fully characterized by 1 H NMR,IR,EA,MS,and X-ray crystal diffraction.Ligand L3(C16H20N2,Mr=240.34)belongs to the triclinic system,space group P1,with a=7.9606(19),b=9.028(2),c=11.205(3)?,the final R=0.0606 and wR=0.1875.Complex 3(C32H38N4Ni,Mr=537.37)belongs to the monoclinic system,space group C2/c with a=19.811(3),b=11.262(2),c=26.004(4)?,the final R=0.0388 and wR=0.1020.The crystal structures indicated that all the NiⅡcomplexes have similar tetra-coordinated geometries,in which the ligand chelated to the center nickel with a 2:1 molar ratio.Catalytic properties of the NiⅡcomplexes for ethylene polymerization were systematically investigated,and the results showed a regular increase of catalytic activities with steric hindrance of the substituents on the imino-aryl ring of NiⅡcomplexes.
基金
supported by the National Natural Science Foundation of China (No. 51674200)
the Science and Technology Research Program of Shaanxi Province (2019JM-421,2018JM2035)。
