Schulich Faculty of Chemistry , Technion - Israel Institute of Technology , Haifa City , 32000 , Israel.
Institut für Anorganische und Analytische Chemie , Technische Universität Braunschweig , Hagenring 30 , 38106 Braunschweig , Germany.
Inorg Chem. 2019 Oct 7;58(19):13426-13439. doi: 10.1021/acs.inorgchem.9b02324. Epub 2019 Sep 26.
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.
本文报道了一系列新型的含（苯）咪唑啉-2-亚氨基配体的铝、镁和锌配合物的合成与表征。在不同的反应条件下，（苯）咪唑啉-2-亚胺配体与金属烷基前体反应，得到相应的配合物，呈现单核、双核和三核结构。在室温下以 1:1 的化学计量比反应得到简单的路易斯酸碱加合物，其金属中心周围呈现出扭曲的四面体形几何形状；而高温反应则生成二聚体配合物，其中每个金属桥接两个（苯）咪唑啉-2-亚胺配体，在配合物的中心形成一个四元金属环。以这些配合物为前体催化剂，在异丙醇的存在下，对ε-己内酯的开环聚合（ROP）进行了研究，观察到非常高的活性，得到了具有低多分散指数的高分子量/中等分子量的聚（ε-己内酯）产物。详细的动力学研究表明，聚合反应以活性方式进行，并且聚合物的分子量可以精确控制。
