yields. All of these complexes are fully characterized. X-ray structural determination revealed that complexes 1−6 are isostructural and have a solvated monomeric structure. The coordination geometry around each of the rare-earth metal atoms can be best described as a distorted trigonal bipyramid. It was found that complexes 1−6 are efficient initiators for the ring-opening polymerization of l-lactide, and
合成了由
咪唑烷桥联的双(
酚基)
配体负载的一系列中性稀土
金属酰胺,并探讨了它们对1-
丙交酯聚合的催化活性。Ln [N(TMS)2 ] 3(μ-Cl)Li(THF)3与H 2 [ONNO] H 2 [ONNO] = 1,4-双(2-羟基-3,5) -二叔丁基-苄基)-
咪唑烷}在
四氢呋喃(THF)中以1:1的摩尔比得到中性稀土
金属酰胺[ONNO] Ln [N(TMS)2 ](THF)[Ln = La (1),Pr(2),Nd(3),Sm(4),Yb(5)和Y(6)]的高分离产率。所有这些复合物均已充分表征。X-射线结构测定表明,配合物1 - 6是同构的,并且具有溶剂化的单体结构。每个稀土
金属原子周围的配位几何可以最好地描述为扭曲的三角双锥体。结果发现,复合体1 - 6是的开环聚合
引发剂高效升-
丙交酯,和中央
金属的离子半径对催化活性的影响显著。进一步的研究表明,这些稀土
金属酰胺可以发起升-
丙交酯在1当量
异丙醇的存在下以受控方式聚合。