Constrained Geometry Tetramethylcyclopentadienyl-phenoxytitanium Dichlorides: Template Synthesis, Structures, and Catalytic Properties for Ethylene Polymerization

The synthesis of four new bidentate ligands, 2-(tetramethylcyclopentadienyl)-4,6-di-tert-butylphenol ((TCDBP)H2, 5), 2-(tetramethylcyclopentadienyl)-6-tert-butylphenol ((TCBP)H2, 6), 2-(tetramethylcyclopentadienyl)-6-phenylphenol ((TCPP)H2, 7), and 2-(tetramethylcyclopentadienyl)-6-methylphenol ((TCMP)H2, 8), as well as their corresponding constrained
geometry tetramethylcyclopentadienyl-phenoxytitanium dichlorides (TCDBP)TiCl2 (9), (TCBP)TiCl2 (10), (TCPP)TiCl2 (11), and (TCMP)TiCl2 (12) are described. A new method for the
synthesis of complexes 9−12 was developed. Molecular structures of 9, 10, and 11 were
determined by single-crystal X-ray diffraction. The Cp(cent)−Ti−O angles of 106.8° for 9,
107.1° for 10, and 107.3° for 11 reveal their sterically open features as catalyst precursors.
When activated with iBu3Al and Ph3C+B(C6F5)4-, complexes 9−12 exhibit reasonable catalytic
activity for ethylene polymerization, producing polyethylenes with moderate molecular
weights and melting points.

本文报道了四种新型双齿配体——2-(四甲基环戊二烯基)-4,6-二叔丁基苯酚((TCDBP)H₂, 5)、2-(四甲基环戊二烯基)-6-叔丁基苯酚((TCBP)H₂, 6)、2-(四甲基环戊二烯基)-6-苯基苯酚((TCPP)H₂, 7)与2-(四甲基环戊二烯基)-6-甲基苯酚((TCMP)H₂, 8)——及其对应的受限几何结构四甲基环戊二烯基苯氧基二氯化钛配合物：(TCDBP)TiCl₂ (9)、(TCBP)TiCl₂ (10)、(TCPP)TiCl₂ (11)及(TCMP)TiCl₂ (12)的合成。此外，本文开发了一种合成配合物9~12的全新方法。通过单晶X射线衍射测定了配合物9、10和11的分子结构。配合物9的Cp(中心)−Ti−O键角为106.8°，配合物10为107.1°，配合物11为107.3°，这表明它们作为催化剂前驱体具备空间开放的结构特征。当以三异丁基铝(iBu₃Al)与三苯碳鎓四(五氟苯基)硼酸盐(Ph₃C⁺B(C₆F₅)₄⁻)活化时，配合物9~12对乙烯聚合展现出良好的催化活性，所得聚乙烯具有适中的分子量与熔融温度。