title: Synthesis, structure and catalytic activity of alkali metal-free bent-sandwiched lanthanide amido complexes with calix[4]-pyrrolyl ligands.
abstract: Simple silylamine elimination reactions of calix[4]-pyrrole [R(2)C(C(4)H(2)NH)](4) (R = Me (1), {-(CH(2))(5)-}(0.5) (2)) with 2 equiv. of [(Me(3)Si)(2)N](3)Ln(μ-Cl)Li(THF)(3) (Ln = Nd, Sm, Dy) in reflux toluene, afforded the novel dinuclear alkali metal-free trivalent lanthanide amido complexes (η(5):η(1):η(5):η(1)-R(8)-calix[4]-pyrrolyl){LnN(SiMe(3))(2)}(2) (R = Me, Ln = Nd (3), Sm (4), Dy (5); R = {-(CH(2))(5)-}(0.5), Ln = Nd (6), Sm(7)). The complexes were fully characterized by elemental analyses, spectroscopic analyses and single-crystal X-ray analyses. X-ray diffraction studies showed that each lanthanide metal was supported by bispyrrolyl anions in an η(5) fashion and along with three nitrogen atoms from N(SiMe(3))(2) and two other pyrroyl rings in η(1) modes formed the novel bent-sandwiched lanthanide amido bridged trivalent lanthanide amido complexes, similar to ansa-cyclopentadienyl ligand-supported lanthanide amides with respect to each metal center. The catalytic activities of these organolanthanide complexes as single component l-lactide polymerization catalysts were studied.
authors.affiliation: Anhui Laboratory of Molecule-Based Materials, School of Chemistry and Materials Science, Anhui Normal University, Wuhu, Anhui 241000, P. R. China.
authors.forename: Shuangliu
authors.initials: S
authors.lastname: Zhou
authors.forename: Shihong
authors.initials: S
authors.lastname: Wu
authors.forename: Hong
authors.initials: H
authors.lastname: Zhu
authors.forename: Shaowu
authors.initials: S
authors.lastname: Wang
authors.forename: Xiancui
authors.initials: X
authors.lastname: Zhu
authors.forename: Lijun
authors.initials: L
authors.lastname: Zhang
authors.forename: Gaosheng
authors.initials: G
authors.lastname: Yang
authors.forename: Daohui
authors.initials: D
authors.lastname: Cui
authors.forename: Hengyu
authors.initials: H
authors.lastname: Wang