A series of β-quinolyl-enamino aluminium complexes [AlLMe₂] 1–7 {L = [(2-C₉H₆N)-CHC(4-MeC₆H₄)-N(Ar)–], Ar = C₆H₅ (1), 4-FC₆H₄ (2), 3,4,5-F₃C₆H₂ (3), C₆F₅ (4), 5-^tBuC₆H₄ (5), 2,6-Me₂C₆H₃ (6), and 2,6-ⁱPr₂C₆H₃ (7)} were synthesized by the reaction of AlMe₃ with the corresponding β-quinolyl-enamine ligands. All the complexes were characterized by ¹H and ¹³C NMR spectroscopy and elemental analysis. The molecular structures of complexes 1–3 and 7 were confirmed by single-crystal X-ray diffraction, which revealed that all the Al atoms adopt a distorted tetrahedral geometry. These Al complexes were tested as the initiators for the ring-opening polymerization (ROP) of ε-caprolactone (ε-CL). The polymerization results showed that 1–5 in the presence of BnOH proceeded efficiently and their catalytic behaviors toward the ROP of ε-CL were significantly affected by the substituents of the aryl ring (Ar) on the end of the enamino framework, where the placement of electron-withdrawing substituents caused higher catalytic activity. However 6 and 7 displayed poor activity under the same conditions, suggesting that ortho-substituents on the Ar moieties hamper the coordination–insertion of the ε-CL monomer. The ROP of ε-CL by efficient binary catalytic systems proceeded in a living manner evidenced by the narrow PDIs and the linear nature of M_nversus conversion plots and monomer/catalyst ratios.

中文翻译：

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β-喹啉基-烯氨基铝配合物催化ε-己内酯的活性开环聚合：配体电子效应†

一系列β-喹啉基-烯氨基铝配合物[AlLMe ₂ ] 1–7 {L = [（2-C ₉ H ₆ N）-CH C（4-MeC ₆ H ₄）-N（Ar）–]，Ar = C ₆ H ₅（1），4-FC ₆ H ₄（2），3,4,5-F ₃ C ₆ H ₂（3），C ₆ F ₅（4），5- ^t BuC ₆ H ₄（5），2,6-Me ₂ C ₆ H通过AlMe ₃与相应的β-喹啉基-烯胺配体的反应合成了图₃（ 6）和_2，6 - ⁱ Pr ₂ C ₆ H ₃（ 7）}。所有配合物均通过¹ H和¹³ C NMR光谱学和元素分析表征。配合物1-3和7的分子结构已通过单晶X射线衍射确认，这表明所有Al原子均采用扭曲的四面体几何形状。测试了这些Al络合物作为ε-己内酯（ε-CL）开环聚合（ROP）的引发剂。聚合结果表明1-5在BnOH的存在下有效地进行，并且其朝向ε-CL的ROP催化行为由芳环（Ar）的对烯胺框架的端部，所述取代基分别显著的影响，其中的吸电子取代基的放置引起较高的催化活性。然而，6和7在相同条件下显示出较差的活性，这表明Ar部分上的邻位取代基阻碍了ε-CL单体的配位-插入。高效的二元催化体系对ε-CL的ROP以生动的方式进行，这由窄的PDI和M _n与转化率图和单体/催化剂比的线性关系证明。