Bis(imino)aryl NCN pincer aluminum and zinc complexes: Synthesis, characterization, and catalysis on L -lactide polymerization

Zhizhou Liu, Wei Gao, Jingshun Zhang, Dongmei Cui, Qiaolin Wu, Ying Mu

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70 Citations (Scopus)

Abstract

Reactions of 2,6-(ArN=CH)2C6H3Li with AlEt2Cl afford a number of NCN pincer aluminum complexes (2,6-(ArN=CH)2C6H3)AlEt2 (Ar = Ph (1), 2,6-Me2C6H3 (2), 2,6-Et2C 6H3 (3), 2,6-iPr2C6H 3 (4)). Similar reactions of 2,6-(ArN=CH)2C 6H3Li with ZnEtCl produce bisligated zinc complexes (2,6-(ArN=CH)2C6H3)2Zn (Ar = Ph (5), 2,6-Me2C6H3 (6), 2,6-Et2C 6H3 (7)) and monoligated NCN pincer zinc complex (2,6-(ArN=CH)2C6H3)ZnEt (Ar = 2,6- iPr2C6H3 (8)). All complexes were characterized by 1H and 13C NMR spectroscopy, and the molecular structures of complexes 3, 4, 6, 7, and 8 were determined by X-ray crystallography. The X-ray diffraction analysis reveals that both complexes 3 and 4 adopt a distorted trigonal-bipyramidal geometry around the aluminum central metal with three carbon atoms in the equator and the two imine nitrogen atoms in the apical positions. Complexes 6 and 7 adopt a distorted tetrahedral geometry around their zinc metal centers, while complex 8 adopts a square-planar geometry around its metal center. All these Al and Zn complexes are efficient initiators for l-lactide ring-opening polymerization in the presence of benzyl alcohol, and the polymerization reaction takes place in an immortal manner. The productivity of the Zn complexes is generally higher than that of the Al complexes under similar conditions.

Original languageEnglish
Pages (from-to)5783-5790
Number of pages8
JournalOrganometallics
Volume29
Issue number22
DOIs
Publication statusPublished - 22 Nov 2010
Externally publishedYes

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