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Highly efficient magnesium initiators for lactide polymerization.
Jolanta Ejfler1, Michał Kobyłka, Lucjan B Jerzykiewicz
1Faculty of Chemistry, University of Wroclaw, 14, F. Joliot-Curie, 50383 Wroclaw, Poland.
Dalton Transactions (Cambridge, England : 2003)
|May 24, 2005
Summary
Bulky aminophenolate ligands stabilize monomeric magnesium complexes, which are effective initiators for lactide polymerization. These ligands act as both stabilizing agents and active polymerization groups, enabling efficient polymer synthesis.
Area of Science:
- Organometallic Chemistry
- Polymer Science
- Catalysis
Background:
- Magnesium complexes are increasingly explored as catalysts in polymerization reactions.
- Developing stable and active initiators is crucial for controlled polymer synthesis.
Purpose of the Study:
- To synthesize and characterize novel magnesium complexes with bulky aminophenolate ligands.
- To evaluate their efficacy as initiators for lactide polymerization.
Main Methods:
- Preparation and characterization of magnesium complexes [(Htbpoa)2Mg] (1) and [(Htbpca)2Mg(THF)2] (2).
- X-ray crystallography to determine the structure of complex 1.
- Lactide polymerization experiments using the synthesized complexes as initiators.
Main Results:
- Two monomeric, six-coordinated magnesium complexes with bulky aminophenolate ligands were successfully prepared and characterized.
- The crystal structure of [(Htbpoa)2Mg] (1) revealed a six-coordinate magnesium center stabilized by two tridentate ligands.
- Complex 1 exists in equilibrium with a five-coordinate species in solution, featuring a dangling oxolane fragment.
- Both complexes demonstrated activity as initiators for lactide polymerization.
Conclusions:
- Bulky aminophenolate ligands effectively stabilize monomeric magnesium species.
- These ligands play a dual role, acting as both ancillary ligands and polymerization initiating groups.
- The synthesized magnesium complexes are promising initiators for lactide polymerization.