Synthesis Of Dinuclear Group 4 Metal Complexes Bearing Bifunctional Amine-Ether Ligand And Their Application For Olefine Polymerization

Olefin-based materials are lightweight,cost-competitive,display broad-ranging material properties,high chemical inertness,and good recyclability.While these properties meet basic market needs and recent sustainable development requirements,modern market needs are becoming more diverse.Polyolefin catalysts is the core in researching of polyolefin materials.In this thesis,five different metal catalysts were designed and synthesized based on early-transition metal catalysts with the structural diversity of ligands,high activity,high selectivity,and polymer microstructure controllability.The structures of metal complexes and related ligand were confirmed by nuclear magnetic resonance,elemental analysis and XRD-single crystal diffraction.The catalytic performance of the catalysts were tested under different polymerization conditions.The main work of this thesis is summarized as follows:Synthesis of three corresponding ligands bearing anthracene（syn-L,anti-L and mono-L）,and the corresponding five metal complexes were generated in situ with M（NMe₂）₄ at room temperature（syn-Ti₂,syn-Zr₂,syn-Hf₂,anti-Hf₂ and mono-Hf₁）.The metal complexes are confirmed by nuclear magnetic resonance（NMR）,elemental analysis and XRD-single crystal ray diffraction.The analysis of the single crystal diffraction results of syn-Hf₂,syn-Hf₂ and anti-Hf₂ shows that the complex presents an approximate triangular bipyramid geometry around the metal center.In complex syn-Hf_2,the distance between the two metal hafnium centers Hf1…Hf2 is 7.321?,on both sides of the anthracene plane.Similarly,the distance between the two metal titanium centers Ti1…Ti2 is 7.138?in syn-Ti₂.However,the distance of the two metals is 8.807?in anti-Hf₂,which is larger than that in syn-Hf₂.Subsequently,we explored the catalytic performance of these five metal complexes for homo-polymerization of ethylene and the copolymerization withα-octene,in the presence of Et₃Al/Ph₃B[(C₆F₅]₄]as cocatalyst.The results show that the catalytic activity,high temperature resistance and polymerization controllability syn-Ti₂>syn-Zr₂>syn-Hf₂ when the catalyst ligand structure is the same;when the metal center is the same,the catalytic activity of different metal spacing is syn-Hf₂>anti-Hf₂>mono-Hf₂,among which syn-Hf₂ showed the highest catalytic activity and produced polymers with the narrowest（PDI=2.79）.