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α,α'-Bis (imino)-2,3:5,6-bis (pentamethylene)pyridines appended with benzhydryl and cycloalkyl substituents: Probing their effectiveness as tunable N,N,N-supports for cobalt ethylene polymerization catalysts
Applied Organometallic Chemistry ( IF 3.7 ) Pub Date : 2021-09-06 , DOI: 10.1002/aoc.6429
Mingyang Han 1, 2 , Ivan I. Oleynik 3 , Yanping Ma 1 , Irina V. Oleynik 3 , Gregory A. Solan 1, 4 , Tongling Liang 1 , Wen‐Hua Sun 1, 2, 5
Affiliation  

A single-pot method has been utilized to prepare the bis(cycloheptyl)fused N,N,N-cobalt (II) chloride complexes, [2,3:5,6-{C4H8C(NAr)}2C5H3N]CoCl2 (Ar = 2,6-(C5H9)2–4-(CHPh2)C6H2 Co1, 2-(C5H9)-4,6-(CHPh2)2C6H2 Co2, 2-(C6H11)-4,6-(CHPh2)2C6H2 Co3, 2-(C8H15)-4,6-(CHPh2)2C6H2 Co4, 2-(C12H23)-4,6-(CHPh2)2C6H2 Co5) in reasonable yields. The molecular structure of Co1 highlights not only the steric shielding of the metal center provided by the N-2,6-dicyclopentyl-4-benzhydrylphenyl groups but also the trans-configuration of the puckered sections of the two fused seven-membered rings. Besides this structural characterization, all complexes have been characterized by elemental analysis and Fourier transform infrared spectroscopy (FT-IR) spectroscopy. In the presence of modified methylaluminoxane (MMAO) or methylaluminoxane (MAO), Co1Co5 afforded highly linear polyethylenes (Tm′s > 126°C) with dispersities that were influenced by the type of aluminoxane activator [Mw/Mn range: 1.53–1.81 (MMAO) vs. 8.96–15.5 (MAO)]. In common to both co-catalysts, the catalytic activity of the precatalysts fell in the order: Co1 > Co2 > Co5 > Co4 ~ Co3, reflecting the differences in steric/electronic properties of the ortho-cycloalkyl substituents. In terms of thermostability of the catalyst, Co1/MMAO attained optimal performance at 30°C (2.04 × 106 g PE mol−1[Co] h−1), while Co1/MAO reached it at 60°C albeit with lower productivity (0.70 × 106 g PE mol−1[Co] h−1). In general, the polyethylenes were of reasonably high molecular weight (e.g., between 39.9 and 65.8 kg mol−1 using MMAO) which can be linked to the steric hindrance imposed on chain transfer by the cycloalkyl and benzhydryl ortho-substituents.

中文翻译:

α,α'-双(亚氨基)-2,3:5,6-双(五亚甲基)吡啶附加二苯甲基和环烷基取代基:探索它们作为可调谐 N,N,N-载体用于钴乙烯聚合催化剂的有效性

单锅法已被用于制备双(环庚基)稠合N,N,N-钴 (II) 氯化物配合物,[2,3:5,6-{C 4 H 8 C(NAr)} 2 C 5 H 3 N]CoCl 2 (Ar = 2,6-(C 5 H 9 ) 2 –4-(CHPh 2 )C 6 H 2 Co1 , 2-(C 5 H 9 )-4,6-(CHPh 2 ) 2 C 6 H 2 Co2 , 2-(C 6 H 11 )-4,6-(CHPh 2 ) 2C 6 H 2 Co3 , 2-(C 8 H 15 )-4,6-(CHPh 2 ) 2 C 6 H 2 Co4 , 2-(C 12 H 23 )-4,6-(CHPh 2 ) 2 C 6 H 2 Co5 ) 的合理产率。Co1的分子结构不仅突出了N -2,6-二环戊基-4-二苯甲基苯基提供的金属中心的空间屏蔽,而且突出了反式-两个稠合七元环的褶皱部分的构型。除了这种结构表征外,所有配合物都通过元素分析和傅里叶变换红外光谱 (FT-IR) 光谱进行了表征。在改性甲基铝氧烷 (MMAO) 或甲基铝氧烷 (MAO) 存在下,Co1Co5提供高度线性的聚乙烯(T m 's > 126°C),其分散度受铝氧烷活化剂类型的影响 [ M w / M n范围:1.53–1.81 (MMAO) 与 8.96–15.5 (MAO)]。两种助催化剂的共同点是,前催化剂的催化活性依次下降:Co1  >  Co2  > Co5  >  Co4  ~  Co3,反映了环烷基取代基空间/电子性质的差异。在催化剂的热稳定性方面,Co1 /MMAO 在 30°C 下达到最佳性能(2.04 × 10 6  g PE mol -1 [Co] h -1),而Co1 /MAO 在 60°C 下达到最佳性能,但生产率较低(0.70 × 10 6  g PE mol -1 [Co] h -1 )。通常,聚乙烯具有相当高的分子量(例如,介于 39.9 和 65.8 kg mol -1使用 MMAO),它可以连接到环烷基和二苯甲基邻位取代基对链转移施加的空间位阻。
更新日期:2021-09-06
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