Bimetallic salen aluminum complexes: Cooperation between reactive centers in the ring-opening polymerization of lactides and epoxides
| Autor: | Luana Lettieri, Konstantin Press, Ilaria D'Auria, Florence Isnard, Marina Lamberti, Rubina Troiano, Mina Mazzeo |
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| Jazyk: | angličtina |
| Rok vydání: | 2016 |
| Předmět: |
Magnetic Resonance Spectroscopy
Stereochemistry Stereoisomerism 010402 general chemistry 01 natural sciences Ring-opening polymerization Catalysis Polymerization Dioxanes Inorganic Chemistry chemistry.chemical_compound Elimination reaction Polymer chemistry Cyclohexenes Organometallic Compounds Molecule Alkyl chemistry.chemical_classification Molecular Structure 010405 organic chemistry Ligand Ethylenediamines 0104 chemical sciences chemistry Salen ligand Spectrometry Mass Matrix-Assisted Laser Desorption-Ionization Epoxy Compounds |
| Popis: | Three dinuclear aluminum alkyl complexes of the general formula LAl2Me4, where L are salen ligands with an alkyl backbone of different lengths between the nitrogen atoms (1,3-propylene (1), 1,5-pentylene (2) and 1,12-dodecaylene (3)), have been prepared through alkane elimination reactions between each ligand and two equivalents of AlMe3. The related hemi-salen aluminum complex 4 was prepared by an analogous reaction between a phenoxy–imine ligand and a single equivalent of AlMe3. The activities of these aluminum complexes in the ring-opening polymerization (ROP) of rac-lactide and of several epoxides have been investigated and compared. The dinuclear complex 1, bearing the salen ligand with the shortest alkyl bridge, was the most active in the ROP of LA producing isotactic enriched PLA. Otherwise, the other complexes (2 and 3), in which the metal centers are remote, produced atactic PLA with inferior activity. Analogous differences in terms of activity emerged in the ROP of epoxides. The comparison of the catalytic behavior of the dinuclear complexes as well as their mononuclear counterparts suggests the cooperation between the two aluminum metal centers of the dinuclear species in which these are close enough. |
| Databáze: | OpenAIRE |
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