NDLI: Bimetallic lanthanide amido complexes as highly active initiators for the ring-opening polymerization of lactides

Content Provider	World Health Organization (WHO)-Global Index Medicus
Author	Sun, Song Tan, Yufang Yao, Yingming Nie, Kun Zhao, Bei Zhang, Yong Shen, Qi
Description	Author Affiliation: Sun S ( Key Laboratory of Organic Synthesis of Jiangsu Province, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, People's Republic of China.)
Abstract	A series of neutral bimetallic lanthanide amido complexes supported by rigid phenylene bridged bis(β-diketiminate) ligands were synthesized, and their catalytic behavior for the polymerization of L-lactide and rac- lactide was explored. The amine elimination reaction of $Ln[N(TMS)_{2}]_{3}(μ-Cl)Li(THF)_{3}$ with $PARA-H_{2},$ $[PARA-H_{2}$ = $2[2,6-^{i}Pr_{2}C_{6}H_{3}NHC(Me)C(H)C(Me)N]-(para-phenylene)]$ in a 2:1 molar ratio in THF at 25 °C afforded the corresponding bimetallic lanthanide amido complexes $PARA-\{Ln[N(SiMe_{3})_{2}]_{2}\}_{2}$ [Ln = Nd(1), Sm(2), Y(3)] in high isolated yields. Similar reaction of $Nd[N(TMS)_{2}]_{3}(μ-Cl)Li(THF)_{3}$ with $META-H_{2},$ $[META-H_{2}$ = $2[2,6-^{i}Pr_{2}C_{6}H_{3}NHC(Me)C(H)C(Me)N]-(meta-phenylene)]$ at 90 °C in toluene for about 48 h gave $META-\{Nd[N(SiMe_{3})_{2}]_{2}\}_{2}$ (4). Complexes 1–4 were well characterized by elemental analysis , IR spectroscopy , and their definitive structures were confirmed by an X-ray crystal structure analysis. The coordination environment and coordination geometry around the metal atoms are similar in these complexes. Each of the metal atoms is four-coordinated with two nitrogen atoms from the N,N-chelating β-diketiminate unit, and two nitrogen atoms from two $(Me_{3}Si)_{2}N–$ groups to form a distorted tetrahedron. These complexes can serve as highly active initiators for L-lactide polymerization in toluene . In addition, they also showed high activity towards rac-lactide polymerization in THF at room temperature, giving heterotactic-enriched polymers $(P_{r}$ ≈ 0.70), and complex 4 displays obviously higher activity in comparison with complex 1.
ISSN	14779226
Issue Number	8
Volume Number	42
e-ISSN	13645447
Journal	Dalton Trans.
Language	English
Publisher	Royal Society of Chemistry
Publisher Date	2013-02-28
Publisher Place	Great Britain (UK)
Access Restriction	Subscribed
Subject Keyword	Amides Chemistry Dioxanes Chemical Synthesis Lanthanoid Series Elements Organometallic Compounds Models, Molecular Molecular Structure Polymerization Journal Article Research Support, Non-U.S. Gov't
Content Type	Text
Resource Type	Article
Subject	Inorganic Chemistry

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