A series of calcium complexes supported by NNO-tridentate ketiminate ligands have been synthesized and characterized. X-ray structural studies indicate that these complexes bear a mononuclear feature with hexa-coordinated calcium centers bonding to two ketiminate ligands. Polymerization of L-lactide catalyzed by these complexes proceeds rapidly and well controlled in the presence of a variety of alcohols. In addition, these complexes reveal good catalytic activity even with the addition of up to 80 equiv. of benzyl alcohol as a transfer agent. Furthermore, kinetic studies show ROP of L-lactide is a first-order dependency on [LA] and a second-order dependency on [BnOH].
我们合成并鉴定了一系列由 NNO-三叉酮
亚胺配体支持的
钙络合物。X 射线结构研究表明,这些配合物具有单核特征,六配位
钙中心与两个酮
亚胺配体成键。在这些配合物的催化下,L-内酰胺的聚合反应在多种
醇类存在的情况下均能快速进行,且控制良好。此外,即使添加多达 80 等量的
苯甲醇作为转移剂,这些复合物也能显示出良好的催化活性。此外,动力学研究表明,L-内酰胺的 ROP 与 [
LA] 呈一阶依赖关系,与 [BnOH] 呈二阶依赖关系。