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Xanthene-modified and hangman iron corroles.
Matthias Schwalbe1, Dilek K Dogutan, Sebastian A Stoian
1Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States. matthias.schwalbe@chemie.hu-berlin.de
Inorganic Chemistry
|January 20, 2011
Summary
New iron corrole complexes, including xanthene-modified variants, efficiently catalyze hydrogen peroxide disproportionation. Their catalytic activity correlates with oxidation potential, highlighting their redox activity and potential in oxygen-oxygen bond activation.
Area of Science:
- Inorganic Chemistry
- Organometallic Chemistry
- Catalysis
Background:
- Iron corroles are versatile macrocyclic ligands with applications in catalysis.
- Xanthene scaffolds can be incorporated into iron corroles to modify their properties.
- Understanding the electronic structure and redox behavior of iron corroles is crucial for optimizing their catalytic functions.
Purpose of the Study:
- To synthesize and characterize novel iron corroles functionalized with a xanthene scaffold.
- To investigate the electronic structure and oxidation state of the iron center in these complexes.
- To evaluate the catalytic activity of these iron corroles in the disproportionation of hydrogen peroxide (catalase reaction) and explore structure-activity relationships.
Main Methods:
- Synthesis of iron corroles from readily available starting materials.
- (57)Fe Mössbauer spectroscopy to probe the oxidation state and electronic environment of the iron center.
- Density Functional Theory (DFT) calculations to complement spectroscopic data and elucidate electronic structure.
- Catalytic assays to measure the disproportionation of hydrogen peroxide.
Main Results:
- Successfully synthesized and spectroscopically characterized new iron corroles with xanthene modification.
- Spectroscopic and DFT studies revealed the non-innocent nature of the corrole ligand, with a formal Fe(IV) center and a one-electron oxidized corrole macrocycle, resulting in an Fe(III) center coupled to a monoradical dianion.
- The iron corroles, including xanthene-modified and hangman variants, demonstrated redox activity and catalyzed the catalase reaction, with activity scaling linearly with oxidation potential.
- The meso position of the corrole macrocycle was found to be susceptible to nucleophilic attack during catalysis.
Conclusions:
- The synthesized iron corroles exhibit complex electronic structures with significant ligand non-innocence.
- These iron corroles are effective redox-active catalysts for the catalase reaction, with tunable activity based on their oxidation potential.
- The study underscores the potential of corrole-based complexes, particularly those with tailored scaffolds like xanthene, for catalyzing two-electron transformations of the oxygen-oxygen bond.
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