title: Synthesis and characterization of benzoxazine-functionalized amine bridged bis(phenolate) lanthanide complexes and their application in the ring-opening polymerization of cyclic esters.
abstract: The synthesis and structures of lanthanide complexes supported by benzoxazine-functionalized amine bridged bis(phenolate) ligand 6,6'-(2-(8-tert-butyl-6-methyl-2H-benzo[e][1,3]oxazin-3(4H)-yl)ethylazanediyl)bis(methylene)bis(2-tert-butyl-4-methylphenolato) (L(2-)) are described. Salt metathesis reaction between lanthanide trichloride and 2 eq of LNa(2) in THF at room temperature afforded the corresponding "ate" complexes [L(2)LnNa(THF)(2)] (Ln[double bond, length as m-dash]Y (1), Nd (2), Er (3), Yb (4)). Further treatment of the product with 18-crown-6 afforded discrete ion-pair complexes [L(2)Ln][(18-crown-6)Na(THF)(2)] (Ln[double bond, length as m-dash]Y (5), Yb (6)). The single-crystal structural analyses of 1 and 3-6 revealed that the lanthanide cation and the sodium cation were bridged by two phenolate oxygen atoms in complexes 1, 3 and 4, while in complexes 5 and 6, the anion comprises a lanthanide cation coordinated by two L(2-) and the cation is comprised of a sodium cation surrounded by an 18-crown-6 and two THF molecules. These complexes were found to exhibit distinct activities towards the ring-opening polymerization of ε-caprolactone and l-lactide.
authors.affiliation: MOE Key Laboratory of Macromolecular Synthesis and Functionalization, Department of Polymer Science and Engineering, Zhejiang University, Hangzhou, China.
authors.forename: Zhenhua
authors.initials: Z
authors.lastname: Liang
authors.forename: Xufeng
authors.initials: X
authors.lastname: Ni
authors.forename: Xue
authors.initials: X
authors.lastname: Li
authors.forename: Zhiquan
authors.initials: Z
authors.lastname: Shen