【作者】 李爱科；

【导师】 黄吉玲；

【作者基本信息】 华东理工大学 ， 有机化学， 2014， 博士

【摘要】 本文共合成了18个未见文献报道的新型钛族金属络合物,其中包括以双齿[NO]苯氧基亚胺类配体合成了8个双(苯氧基亚胺)钛、锆络合物、1个单(苯氧基亚胺)钛络合物和1个酚氧基单齿配位的锆络合物,以及以三齿[NNO]酚氧亚胺(或酚胺)类配体合成了6个八配位锆络合物和2个钛异丙氧基络合物。所得络合物均通过了1H NMR和EA的分析鉴定,其中部分通过了13C NMR的分析鉴定,并对其中4个具有典型结构的锆络合物(Zrl, Zr6, Zr12和Zr16)进行了X-ray单晶衍射分析,进一步确定了分子结构。在助催化剂MMAO活化下,详细研究了所得钛、锆络合物催化烯烃聚合反应的催化性能。此外,还详细研究了系列单噻吩基取代二茂钛络合物(C1-C4)和锆络合物(C5-C8)催化烯烃聚合反应,并通过X-ray单晶衍射分析测定了此类钛络合物(C2和C4)的分子结构。主要研究工作如下：1.通过在芳胺邻位引入二芳基甲基(CHAr2),合成了10个芳胺邻位大位阻取代的苯氧基亚胺配体,进而合成了8个新型锆络合物,其中,对于芳胺邻位单边大位阻(CHAr2)取代的苯氧基亚胺配体而言,均得到了具有典型结构的双(苯氧基亚胺)锆络合物Zr4-Zr10,当芳胺邻位双边均含有大位阻取代基(CHAr2)时,制得了酚氧基单齿配位的锆络合物Zr1。在MMAO活化下,此类锆络合物均能高活性的催化乙烯聚合,其中,芳胺邻位只有单边取代的锆络合物Zr4不仅具有最高的催化活性84.90×106gPE (mol of Zr)-1h-1,还具有较好的热稳定性,即使在聚合温度为90℃的条件下仍能保持很高的催化活性34.32×106g PE (mol of Zr)-1h-1。所有锆络合物Zr1和Zr4-Zr10均得到了低分子量的聚乙烯(Mv1.4-38.9×103g/mol),1H NMR分析表明所得聚乙烯的链端不存在饱和双键,这说明在芳胺邻位引入取代基的空间位阻过大时,能显著提高聚合增长链向助催化剂转移的速率,因此,在聚合过程中生成了低分子量以铝为端基的聚乙烯(Al-PE)。2.通过此类苯氧基亚胺配体合成了2个新型钛络合物,当芳胺邻位单边大位阻(CHPh2)取代时,得到了双(苯氧基亚胺)钛络合物Ti5,当芳胺邻位双边大位阻(CHPh2)取代时,得到了单(苯氧基亚胺)钛络合物Ti3。在MMAO活化下,钛络合物Ti3和Ti5在催化乙烯聚合时均表现出中等程度的催化活性,其中钛络合物Ti5的催化活性略高,最高为3.8×105g PE(mol of Ti)-1h-1。与锆络合物Zr1和Zr4-Zr10相比,钛络合物Ti3得到了高分子量聚乙烯(Mv42.2-160.5×104g/mol),而钛络合物Ti5所得聚乙烯的分子量更高,在测定粘均分子量的条件下均不能完全溶解,选择部分聚乙烯样品进行高温GPC测定其分子量(Mw)为298.8×104g/mol,表明得到了超高分子量聚乙烯。3.通过合成的取代邻氨基酚与取代吡啶醛经缩合反应得到了5个三齿酚氧亚胺配体(L11H-L14H和L17H),三齿酚氧亚胺配体L12H和L13H经硼氢化钠还原得到了2个三齿酚胺配体(L15H, L16H),在此类三齿配体的基础上,成功的合成了6个三齿配体配位的八配位锆络合物,其中锆络合物Zrll-Zr14含有三齿酚氧亚胺配体,而络合物Zr15和Zr16含有三齿酚胺配体。锆络合物Zr12和Zr16的单晶结构表明,中心金属锆原子同时与两个三齿配体和两个氯原子配位,所形成的八配位锆络合物为扭曲四方反棱柱构型。在MMAO活化下,此类锆络合物Zr11-Zrl6可以高活性的催化乙烯聚合获得高分子量聚乙烯(Mv7.2-52.7×104g/mol),在研究聚合温度对催化活性的影响时发现,在70-140℃的温度范围,此类锆络合物的催化活性随着温度的升高而显著增加,均在140℃时表现出更高的催化活性,其中锆络合物Zr15的催化活性最高为1.04×106g PE (mol of Zr)-1h-1,与此同时,即使在此高温条件下还表现出长达5h的催化寿命,这表明催化活性中心具有很好的热稳定性,可以在温度高达到140℃的条件下长时间保持催化活性而不失活。4.以上述三齿配体(L12H和L17H)与等当量的Ci(OiPr)4反应合成了2个钛异丙氧基络合物Ti12和Ti17。在MMAO活化下,此类钛络合物在催化乙烯聚合时表现出中等程度的催化活性,得到了高分子量聚乙烯(Mv19.5-35.9×104g/mol),在80℃的聚合条件下,钛络合物Ti17具有相对较高的催化活性1.17×105g PE(mol of Ti)-1h-1。5.此外,还研究了系列单噻吩基取代二茂钛络合物(C1-C4)和锆络合物(C5-C8)催化乙烯聚合反应。在MAO活化下,此类钛络合物C1-C4表现出中等程度的催化活性,与Cp2TiCl2的催化活性相近,但是却得到了高分子量至超高分子量的聚乙烯(Mv最高为227.1×104g/mol),在室温条件下,钛络合物C3表现出长达9h的催化寿命,远高于同条件下的Cp2TiCl2。在80℃的聚合条件下,与CP2ZrCl2相比,此类锆络合物C5-C8不仅可以获得分子量更高的聚乙烯(Mv23.2-47.1×104g/mol),而且还具有较Cp2ZrCl2更长的催化寿命,其中锆络合物C8的催化寿命在2h以上。更多还原

【Abstract】 Totally eighteen novel complexes were synthesized in this dissertation, including ten six-coordinate zirconium or titanium complexes supported by bidentate ligands (seven bis(phenoxy-imine) zirconium complexes, one bis(phenoxy-imine) titanium complex, one mono(phenoxy-imine) titanium complex and one zirconium complex ligated by two monodentate phenoxy ligands), six eight-coordinate zirconium complexes supported by two tridentate ligands (tridentate phenoxy-imine ligands or tridentate phenoxy-amine ligands) and two five-or six-coordinate alkoxide titanium complexes supported by a tridentate ligand. All of them were characterized by1H NMR and EA. Some of them were also characterized by13C NMR. The molecular structures of four representative zirconium complexes Zrl, Zr6, Zr12and Zr16were further confirmed by single-crystal X-ray diffraction studies. Upon activation with modified methylaluminoxane (MMAO), these zirconium and titanium complexes were investigated as catalyst precursors for ethylene polymerization in detail. On the other hand, a series of titanocenes C1-C4and zirconocenes C5-C8bearing a pendant thiophene group on a cyclopentadienyl (Cp) ring were tested as catalyst precursors for ethylene polymerization. The molecular structures of two representative titanocenes C2and C4were firstly confirmed by single-crystal X-ray diffraction studies. Conclusions are summarized as follows:1. A series of bidentate phenoxy-imine ligands bearing bulky o-bis(aryl)methyl-substituted aryl groups on the aniline moiety were synthesized. Reactions of ZrCl4·2THF with2equiv of lithium salts of ligands L4H-L10H bearing a bulky bis(aryl)methyl substituent afford the desired sex-coordinate bis(phenoxy-imine) zirconium complexes Zr4-Zr10. Unexpectedly, during the attempt to treat ZrCl4·2THF with2equiv of silylated ligand L1H bearing two bulky bis(phenyl)methyl substituents via trimethylsilyl chloride elimination, a biszwitterionic-type adduct zirconium complex (L1H)2ZrCl4(Zrl) was obtained in which the phenoxy-imine groups function as a monodentate phenoxy ligand. Upon activation with MMAO, all zirconium complexes Zr4-Zr10and Zrl exclusively produce linear aluminium-terminated polyethylene (Al-PE) with high activity, suggesting that chain transfer to aluminum is the predominant termination mechanism. It is noteworthy that the introduction of an excessively bulky o-bis(aryl)methyl substituent adjacent to the imine-N produces low molecular-weight Al-PE (Mv1.4-38.9×103g/mol) due to the enhanced rate of chain transfer to alkylaluminium groups during polymerization. Complex Zr4having a single ortho substituent on the aryl rings (R3=H) is more active with an activity up to84.90×106g PE (mol of Zr)-1h-1. Even at90℃, complex Zr4exhibited good thermal stability and still retains a high activity of34.32×106g PE (mol of Zr)-’h-’for ethylene polymerization.2. Reaction of TiCl4with2equiv of the lithium salt of ligand L53H bearing a bulky bis(phenyl)methyl substituent afford the desired sex-coordinate bis(phenoxy-imine) titanium complex Ti5, whereas similar reaction of TiCl4with one equiv of the lithium salt of L3H that bearing two bulky bis(phenyl)methyl substituents gave a sex-coordinate monoligated titanium complex Ti3. In contrast to the case for these zirconium complexes Zr4-Zr10and Zrl, both titanium complexes Ti3and Ti5exhibited moderate catalytic activity and produced much higher molecular weight polyethylene (PE) for ethylene polymerization. For these two complexes, titanium complex Ti5is more active (up to3.8×103g PE (mol of Ti)-1h-1) and produced ultra-high molecular weight polyethylene relative to that of titanium complex Ti3(Mv42.2-160.5×104g/mol). The obtained products are insoluble in decahydronaphthalene at135℃when measured by viscosity method, and selected GPC plot further confirmed the polyethylene product with ultra-high molecular weight (Mw298.8×104g/mol).3. Sex novel eight-coordinate dichloride zirconium complexes Zrll-Zr16with the general formula L2ZrCl2supported by two tridentate [NNO] ligands were synthesized by the reactions of ZrCl4·2THF with2equiv of the corresponding ligands (tridentate phenoxy-imine ligands (L11H-L14H) or tridentate phenoxy-amine ligands (L15H and L16H)). The molecular structures of the representative zirconium complexes Zr12and Zr16were confirmed by single-crystal X-ray diffraction and revealed that the metal center is eight-coordinated by two tridentate [NNO] ligands and two chlorides in a distorted-square-antiprismatic geometry. Upon activation with MMAO, all zirconium complexes Zrll-Zr16displayed notable thermal stability toward ethylene polymerization and produced high molecular weight polyethylene (Mv7.2-52.7×104g/mol) with high activities at high temperatures. The catalytic activity increases consistently with increasing polymerization temperature (70-140℃), and the highest activity of1.04×106g PE (mol of Zr)-1h-1) was achieved at140℃. In particular, a catalytic lifetime of nearly5h was observed for the Zr15/MMAO catalyst system at140℃, suggesting that the resultant active metal center are extremely stable and maintain high activity for a long period of polymerization time (nearly5h) at temperatures up to140℃.4. Two alkoxide titanium complexes Ti12and Ti17supported by a tridentate [NNO] ligand were synthesized via the reactions of Ti(O’Pr)4with one equiv of the corresponding ligands L12H and L17H. Upon activation with MMAO, both titanium complexes Ti12and T117exhibited moderate catalytic activity for ethylene polymerization and produced high molecular weight polyethylene (Mv19.5-35.9×104g/mol). Titanium complex Ti17is more active and the highest activity of1.17×105g PE (mol of Ti)-1h-1was achieved at80℃.5. In addition, a series monopendant thienyl-substituted group4metallocenes (RCp)[Cp-(bridge)-(2-C4H3S)]MCl2[M=Ti (C1-C4); M=Zr (C5-C8)] were tested as catalyst precursors for ethylene polymerization. In the presence of methylaluminoxane (MAO), these titanocenes C1-C4showed long catalytic lifetime (nearly9h) and produced high or ultra-high molecular weight polyethylene (up to227.1×104g/mol) in comparison to that obtained by Cp2TiCl2. At elevated temperature of80℃, these zirconocenes C5-C8showed long catalytic lifetime (at least2h) and produced much higher molecular weight polyethylene (Mv11.2-47.1×104g/mol) in comparison with Cp2ZrCl2.更多还原