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论文类型：期刊论文

发表时间：2010-05-14

发表刊物：DALTON TRANSACTIONS

收录刊物：SCIE、EI、PubMed

卷号：39

期号：18

页面范围：4440-4446

ISSN号：1477-9226

摘要：The hydroxy-and phenoxy-bridged dinuclear zirconium and hafnium complexes 2 and 3 of an amine-pyridine-bis(phenolate) ligand (H(2)L) were prepared from the reaction of Na(2)L and ZrCl(4) in the presence of 0.5 equiv of water in THF, while the reaction of H(2)L with NaH and then with ZrCl(4) in the freshly distilled THF gave an eight-coordinate bis(homoleptic) mononuclear complex L(2)Zr (1). Two homochiral N atoms were created in each complex upon coordination of the unsymmetric tertiary amine ligands to the metal centers. Enantiomeric dinuclear complexes 2 and 3 both undergo spontaneous resolution during crystallization. The molecular structure of each enantiomer of 2 and 3, as well as the structure of 1, was determined by X-ray analysis and the circular dichroism spectra of N(R)N(R)-2 and N(S)N(S)-2 were studied. The racemates of 2 and 3 catalyzed controlled polymerization of rac-lactide in terms of the linearity of molecular weight versus conversion, forming isotactic-rich polylactide in high yields with a narrow polydispersity.