Magnesium complexes based on an amido-bis(pyrazolyl) ligand: Synthesis,crystal structures,and use in lactide polymerization |
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| Authors: | Bing Lian,Christophe M. Thomas,Osvaldo L. Casagrande Jr.,Thierry Roisnel,Jean-Franç ois Carpentier |
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| Affiliation: | 1. Catalyse et Organométalliques, UMR 6226, University of Rennes 1, 35042 Rennes Cedex, France;2. Laboratório de Catálise Molecular, Instituto de Quimica, Universidade Federal do Rio Grande do Sul, Av. Bento Gonçalves, 9500, Porto Alegre, RS 90501-970, Brazil;3. Centre de Diffractométrie X, Sciences Chimiques de Rennes, UMR 6226, Université de Rennes 1, 35042 Rennes, France |
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| Abstract: | The coordination chemistry of the tridentate N,N,N pro-ligand bis[2-(3,5-dimethyl-1-pyrazolyl)ethyl]amine (1, LH) with dialkylmagnesium and monoalkyl magnesium halides has been studied. Reaction of 2 equiv of 1 with Mg(nBu)2 gave bis(amido) complex [L]2Mg (3), which is monomeric in the solid state. Alkane elimination reactions from iPrMgCl and MeMgI with 1 equiv of 1 afforded the corresponding halide complexes {[L]MgCl}2 (4) and {[L]MgI}2 (5), which both feature dimeric structures in the solid state, with a chelating and spanned coordination mode of the tridentate ligand, respectively. Additionally, bis(amido) complex 3 was shown to be active for the ring-opening polymerization of racemic lactide at room temperature to yield atactic polylactides with high initiation efficiencies and relatively narrow polydispersities (Mw/Mn = 1.28–1.34). |
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| Keywords: | Magnesium NNN Ligands Pyrazolyl ligands Ring-opening polymerization |
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