Zhao Ruiguo, Liu Taotao, Wang Liying, Ma Haiyan
Shanghai Key Laboratory of Functional Materials Chemistry and Laboratory of Organometallic Chemistry, East China University of Science and Technology, Shanghai 200237, P. R. China.
Dalton Trans. 2014 Sep 7;43(33):12663-77. doi: 10.1039/c4dt01122h.
A series of titanium trichloride complexes , ligated with claw-type tetradentate aminophenolate ligands were synthesized from the direct reaction of TiCl4(THF)2 with 1 equiv. of the corresponding aminophenol in the presence of triethylamine. For comparison purposes, titanium isopropoxide complexes were also synthesized via the reaction of Ti(O(i)Pr)4 and 1 equiv. of the proligand. Similar reactions of ZrCl4(THF)2 with the corresponding aminophenol ligands in the presence of triethylamine only allowed the isolation of zirconium complex . The X-ray diffraction studies reveal that titanium trichloride complexes , and titanium triisopropoxide complex all possess a distorted octahedral geometry with the tetradentate aminophenolate ligand in cis-O, N, N chelating mode, where the methoxy group of the aryl unit does not coordinate with the metal center in the solid state. Upon activation with MMAO, these titanium and zirconium(iv) complexes exhibited moderate to high catalytic activities for ethylene polymerization at 30-120 °C, producing high-molecular-weight polyethylenes with broad distributions (Mw/Mn = 10.2-34.8). The activities of titanium trichloride complexes are significantly higher than those of titanium isopropoxide and zirconium trichloride complexes at high temperatures. The highest activity of 15 456 kg (mol-Ti h)(-1) could be achieved by titanium trichloride complex with bromo groups on both ortho- and para-positions of the phenolate ring of the ligand at 120 °C.
一系列与爪型四齿氨基酚盐配体配位的三氯化钛配合物，是通过TiCl4(THF)2与1当量相应氨基酚在三乙胺存在下直接反应合成的。为作比较，异丙醇钛配合物也通过Ti(O(i)Pr)4与1当量前体配体反应合成。ZrCl4(THF)2与相应氨基酚配体在三乙胺存在下的类似反应仅能分离出锆配合物。X射线衍射研究表明，三氯化钛配合物和三异丙醇钛配合物均具有扭曲的八面体几何结构，四齿氨基酚盐配体呈顺式-O、N、N螯合模式，其中芳基单元的甲氧基在固态下不与金属中心配位。用MMAO活化后，这些钛和锆(IV)配合物在30 - 120°C下对乙烯聚合表现出中等到高的催化活性，生成分子量分布宽的高分子量聚乙烯（Mw/Mn = 10.2 - 34.8）。在高温下，三氯化钛配合物的活性显著高于异丙醇钛和三氯化锆配合物。在120°C时，配体酚盐环的邻位和对位均带有溴基团的三氯化钛配合物可实现最高活性15456 kg (mol-Ti h)(-1)。
