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Tuning ligand electronics and peripheral substitution on cobalt salen complexes: structure and polymerisation
Linus Chiang1, Laura E N Allan, Juan Alcantara
1Department of Chemistry, Simon Fraser University, 8888 University Drive, Burnaby, BC V5A 1S6, Canada. tim_storr@sfu.ca.
Dalton Transactions (Cambridge, England : 2003)
|September 20, 2013
Summary
Cobalt salen complexes enable controlled polymerisation. Ligand modifications tune reactivity, influencing polymer chain structure and termination mechanisms in organometallic mediated radical polymerisation.
Area of Science:
- Coordination Chemistry
- Polymer Science
- Organometallic Chemistry
Background:
- Salen complexes are versatile ligands in coordination chemistry.
- Organometallic Mediated Radical Polymerisation (OMRP) offers controlled polymer synthesis.
- Tuning ligand electronic properties impacts metal center reactivity.
Purpose of the Study:
- To synthesize and characterize cobalt salen complexes with varying electronic properties.
- To investigate the application of these complexes in reversible-termination OMRP.
- To understand the relationship between ligand structure and polymerisation control.
Main Methods:
- Synthesis and characterization of cobalt salen complexes.
- Single crystal X-ray diffraction, cyclic voltammetry, XPS, EPR spectroscopy, and computational studies.
- Application in OMRP of styrene, methyl methacrylate, and vinyl acetate.
Main Results:
- Structural studies confirm tailorable metal center reactivity influenced by ligand electron-donating ability.
- Polymerisation studies reveal varying cobalt-carbon bond strengths with ligand substitution.
- Observed competing β-hydrogen abstraction and associative exchange mechanisms.
Conclusions:
- Cobalt salen complexes provide tunable platforms for controlled radical polymerisation.
- Ligand design is critical for controlling polymerisation mechanisms and polymer architecture.
- The study elucidates structure-reactivity relationships in RT-OMRP.
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