Pentacoordinate (&mgr;-Oxo)diiron(III) Thiolate Complexes and Dimeric Iron(II) Precursors.

Area of Science:

• Coordination Chemistry
• Bioinorganic Chemistry
• Organometallic Chemistry

Background:

• Sulfur-donor ligands are crucial in stabilizing unusual metal oxidation states.
• (&mgr;-oxo)diiron(III) complexes are important in various biological and catalytic processes.
• Understanding the reactivity of iron complexes with oxygen is key for catalysis and biomimicry.

Purpose of the Study:

• To synthesize and characterize novel (&mgr;-oxo)diiron(III) complexes with N,N'-bis(2-methyl-2-mercaptopropane)-1,5-diazacyclooctane (H(2)bme-daco) and N,N'-bis(mercaptoethyl)-1,5-diazacyclooctane (H(2)bme-daco) ligands.
• To investigate the reactivity of these iron complexes with molecular oxygen and other oxidants.
• To elucidate the structural and electronic properties of the synthesized diiron complexes.

Main Methods:

• Synthesis of diiron(II) and (&mgr;-oxo)diiron(III) complexes.
• X-ray crystallography for structural determination.
• ESI mass spectroscopy, cyclic voltammetry, and EPR spectroscopy for characterization.

Main Results:

• Well-characterized (&mgr;-oxo)diiron(III) complexes were formed in the presence of sulfur donors.
• Optimized conditions using Fe(acac)(3) and O(2) yielded good results for the H(2)bme-daco ligand.
• Both diiron(II) and (&mgr;-oxo)diiron(III) complexes showed instability towards molecular oxygen.
• X-ray crystallography revealed edge-bridged square pyramidal structures for the iron dimers.
• No ligand-based oxygen capture leading to S-oxygenates was observed.

Conclusions:

• The study successfully synthesized and characterized uncommon (&mgr;-oxo)diiron(III) complexes with sulfur-donor ligands.
• The reactivity studies highlight the sensitivity of these complexes to molecular oxygen, suggesting specific handling and synthetic strategies.
• Structural data provides insights into the coordination environment and electronic properties of these diiron species.