Synthesis, Structure and Reactivity of a Mononuclear N,N,O-Bound Fe(II) α-Keto-Acid Complex.

Area of Science:

• Bioinorganic Chemistry
• Organometallic Chemistry
• Coordination Chemistry

Background:

• Non-heme iron enzymes play crucial roles in biological oxidation reactions.
• Understanding the coordination chemistry and reactivity of iron complexes is vital for mimicking enzyme active sites.
• Benzoylformate ligands are relevant in biological systems and coordination chemistry.

Purpose of the Study:

• To synthesize and characterize a mononuclear, facial, N,N,O-bound iron(II) benzoylformate complex.
• To investigate the structural, electronic, and spectroscopic properties of the synthesized complex.
• To explore the reactivity of the iron complex with small molecules like nitric oxide and molecular oxygen.

Main Methods:

• Synthesis of the iron(II) benzoylformate complex using a bulky phenolate ligand (Im^Ph2 NNO^tBu ).
• X-ray crystallography for structural determination.
• Mössbauer, NMR, UV-vis, EPR, and IR spectroscopies for characterization.
• Cyclic voltammetry for electrochemical studies.
• Density Functional Theory (DFT) analysis.

Main Results:

• The first mononuclear, facial, N,N,O-bound iron(II) benzoylformate complex, [Fe(Im^Ph2 NNO^tBu )(BF)], was successfully synthesized.
• The complex features a pentacoordinate iron center and retains structural integrity in solution.
• The iron center exhibits low oxidation potential and reacts with NO to form an {FeNO}⁷ adduct.
• Reaction with O₂ leads to oxidative decarboxylation, forming a diiron(III) benzoate complex, and demonstrates oxygen atom transfer capability.

Conclusions:

• The synthesized iron(II) complex serves as a valuable model for non-heme iron enzyme active sites.
• The complex displays rich reactivity, including NO adduct formation and oxygen atom transfer.
• The findings contribute to the understanding of iron coordination chemistry and its role in catalysis.