Incorporating Sodium to Boost the Activity of Aluminium TrenSal Complexes towards rac -Lactide Polymerisation
Incorporating Sodium to Boost the Activity of Aluminium TrenSal Complexes towards rac -Lactide Polymerisation
复制标题
掺入钠以增强铝 TrenSal 配合物的外消旋-丙交酯聚合活性
DOI：
10.1002/ejic.202200134
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发表时间：
2022
影响因子：
2.3
通讯作者：
Zhou Y
中科院分区：
文献类型：
--
作者：
Zhou Y
基于TrenSal配体[LH3]的四种新型同源和异质金属钠和/或铝配合物已经合成并充分表征，包括单晶X射线衍射实验。虽然[LAl]对丙交酯开环聚合完全不活跃，但加入钠形成异质金属[LNaAlMe]将铝的几何形状从八面体改变为四面体，从而在共引发剂BnOH （kobs=3.19×10−2min−1；室温，甲苯溶剂）存在下具有良好的催化活性和良好的聚合控制。在相同的条件下，同金属钠配合物在丙交酯聚合中表现出比[LNaAlMe]更高的活性，其中[LNa3]非常活跃（kobs=1.21 min−1），但表现出不寻常的二级单体依赖性和较差的聚合控制。1H NMR研究表明，与[LNaAlMe]或[LH2Na]/BnOH的聚合遵循活化单体机制，而[LNa3]通过同时配位插入和活化单体机制起作用。总的来说，与同金属类似物相比，异金属[LNaAlMe]提供了良好的活性和控制的平衡。
Four novel homo‐ and heterometallic sodium and/or aluminium complexes based on the TrenSal ligand,[LH3], have been synthesised and fully characterised, including by single‐crystal X‐ray diffraction experiments. While[LAl]was completely inactive towardsrac‐lactide ring‐opening polymerisation, incorporating sodium to form heterometallic[LNaAlMe]changes the aluminium geometry from octahedral to tetrahedral, leading to good catalytic activity in the presence of co‐initiator BnOH (kobs=3.19×10−2min−1; room temperature, toluene solvent) and good polymerisation control. Under identical conditions, homometallic sodium complexes showed higher activities inrac‐lactide polymerisation than[LNaAlMe], with[LNa3]being extremely active (kobs=1.21 min−1) but displaying unusual second‐order monomer dependency and poor polymerisation control.1H NMR spectroscopic studies suggest that polymerisation with[LNaAlMe]or[LH2Na]/BnOH follows an activated monomer mechanism, whereas[LNa3]operatesviasimultaneous coordination‐insertion and activated monomer mechanisms. Overall, heterometallic[LNaAlMe]provides a balance of good activity and control compared to the homometallic analogues.