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Published on: December 19, 2017
Sulfur versus iron oxidation in an iron-thiolate model complex
Aidan R McDonald1, Michael R Bukowski, Erik R Farquhar
1Department of Chemistry and Center for Metals in Biocatalysis, 207 Pleasant Street SE, University of Minnesota, Minneapolis, Minnesota 55455, USA.
This study reveals a new sulfur oxidation pathway for iron complexes. Without base, peracid reacts with an iron(II) complex to form an iron(II)-sulfinate species, then an oxoiron(IV) complex with a sulfinate ligand.
Area of Science:
- Inorganic Chemistry
- Bioinorganic Chemistry
- Organometallic Chemistry
Background:
- Iron-oxo complexes are crucial in biological oxidation reactions.
- Understanding the reaction mechanisms of iron complexes with oxidants is vital for catalysis.
- The role of base in modulating iron complex reactivity with peracids is not fully understood.
Purpose of the Study:
- To investigate the reaction of an iron(II) complex with peracid in the absence of base.
- To elucidate the mechanism of sulfur oxidation in iron complexes.
- To characterize novel iron species formed during the reaction.
Main Methods:
- UV-vis spectroscopy
- Electrospray Ionization Mass Spectrometry (ESI-MS)
- Mössbauer spectroscopy
- Extended X-ray Absorption Fine Structure (EXAFS) analysis
- Resonance Raman spectroscopy
- Infrared and Raman spectroscopy
Main Results:
- The reaction of [Fe(II)(TMCS)]PF6 with peracid in methanol without base did not form the expected oxoiron(IV) complex.
- A novel iron(II)-sulfinate species ([Fe(II)(TMCS) + 2O](+)) was formed, characterized by O-bound sulfinate.
- A distinct oxoiron(IV) complex containing a metal-bound sulfinate moiety was generated (4).
- A reaction mechanism involving protonation of an oxoiron(IV) intermediate and subsequent sulfur oxidation was proposed.
Conclusions:
- The absence of base alters the reaction pathway of iron complexes with peracids.
- A novel sulfur oxidation mechanism involving iron(II)-sulfinate and oxoiron(IV)-sulfinate intermediates was discovered.
- This research provides new insights into the reactivity and speciation of iron complexes in oxidation reactions.
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