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(Benz)Imidazolin-2-iminato Aluminum, Zinc, and Magnesium Complexes and Their Applications in Ring Opening Polymerization of ε-Caprolactone
Inorganic Chemistry ( IF 4.3 ) Pub Date : 2019-09-26 , DOI: 10.1021/acs.inorgchem.9b02324
Heng Liu 1 , Maxim Khononov 1 , Natalia Fridman 1 , Matthias Tamm 2 , Moris S. Eisen 1
Affiliation  

Synthesis and characterization of a new family of aluminum, magnesium, and zinc complexes supported by (benz)imidazolin-2-iminato ligands are reported herein. Under different reaction conditions, (benz)imidazolin-2-imine ligands reacted with metal alkyl precursors to afford the corresponding complexes, displaying mononuclear, binuclear, and trinuclear structures. Reaction in 1:1 stoichiometry at room temperature afforded the simple Lewis acid–base adducts, which exhibited distorted tetrahedral geometries around the metal centers, whereas high temperature reactions gave rise to dimeric complexes, with each metal bridging two (benz)imidazolin-2-imine ligands to form a four-membered metallacycle ring at the center of the complexes. The catalytic ring opening polymerization (ROP) of ε-caprolactone was studied using these complexes as precatalysts in the presence of isopropanol, and very high activities were observed, affording high/medium molecular weight poly(ε-caprolactone) products with low polydispersity indices. Detailed kinetic studies revealed that the polymerizations proceeded in a living manner and molecular weights of the polymers could be precisely controlled.

中文翻译:

苯并咪唑啉-2-亚氨基铝,锌,镁配合物及其在ε-己内酯开环聚合中的应用

本文报道了由(苯并)咪唑啉-2-亚氨基配体负载的铝,镁和锌配合物的新家族的合成和表征。在不同的反应条件下,(苯并)咪唑啉-2-亚胺配体与烷基金属前体反应,得到相应的配合物,表现出单核,双核和三核结构。在室温下以化学计量比1:1进行反应,得到简单的路易斯酸碱加合物,其在金属中心周围呈现扭曲的四面体几何形状,而高温反应产生二聚体配合物,每种金属桥接两个(苯并)咪唑啉-2-亚胺配体在配合物的中心形成一个四元金属环。在异丙醇存在下使用这些络合物作为预催化剂,研究了ε-己内酯的催化开环聚合(ROP),观察到非常高的活性,从而提供了具有低多分散指数的高/中分子量聚(ε-己内酯)产品。详细的动力学研究表明,聚合反应以活性方式进行,可以精确控制聚合物的分子量。
更新日期:2019-09-26
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