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首页> 外文期刊>Catalysis science & technology >Preparation of zirconium and hafnium complexes containing chiral N atoms from asymmetric tertiary amine ligands, and their catalytic properties for polymerization of rac-lactide
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Preparation of zirconium and hafnium complexes containing chiral N atoms from asymmetric tertiary amine ligands, and their catalytic properties for polymerization of rac-lactide

机译：制备锆和铪复合物含有手性不对称N个原子叔胺配体,它们的催化rac-lactide属性聚合

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摘要

A series of N-(2-pyridylmethyl)-N, N-bis.2'-hydroxy-benzyl) amine ligands were synthesized, and the new asymmetric tertiary amine ligands reacted with ZrCl4 and HfCl4 to give complexes 1-6. The chiral N atoms were created in the complexes upon coordination of the asymmetric tertiary amine ligands to the metal centers. The complexes were used as catalysts for ring-opening polymerization of rac-lactide. The results show that the substituents and structure of the ligands have effects on the activity and stereoselectivity of the catalyst. The stereoselectivity was promoted by the complex containing the ligand with the electron-withdrawing group. Complex 3, with bulkier cumyl groups on the ligand, possesses better stereoselectivity. The complexes are able to catalyze the living control ring-opening polymerization of rac-lactide to afford isotactic-rich polylactide with narrow molecular weight distribution. Kinetic studies reveal that polymerization is of the first order in both monomer and catalyst. The microstructure of the resulting polymer is determined by H-1 NMR homonuclear decoupled spectra. The results show that the isotactic-rich chain is dominant in the prepared polylactide. The P-m value is in the range of 0.67-0.81.
机译：一系列的N - (2-pyridylmethyl) - N,N-bis.2 -hydroxy-benzyl)胺配体合成,新的不对称的三级胺配体反应和ZrCl4 HfCl4配合物1 - 6。在复合物中创建协调不对称的叔胺配体的金属中心。rac-lactide的开环聚合。结果表明,取代基和结构对活动和配体的影响立体选择性的催化剂。由复杂的立体选择性被提拔包含的配体吸电子集团。笨重cumyl组上的配体,具有更好的立体选择性。促进生活的开环控制聚合rac-lactide买得起isotactic-rich聚交酯与狭窄的分子重量分布。聚合是一阶的单体和催化剂。生成的聚合物是由h - NMR核光谱分离出来。isotactic-rich链中占主导地位准备聚交酯。0.67到-0.81之间。

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