A mononuclear nonheme {FeNO}

Area of Science:

• Inorganic Chemistry
• Bioinorganic Chemistry
• Coordination Chemistry

Background:

• {FeNO}7,8,9 complexes are well-studied in heme and nonheme iron models.
• Understanding of {FeNO}6 complexes, particularly in nonheme iron systems, remains limited.

Purpose of the Study:

• To synthesize and characterize mononuclear nonheme {FeNO}6 complexes using a tetraamido macrocyclic ligand (TAML).
• To investigate alternative synthetic routes, including photochemical methods, for generating these complexes.
• To elucidate the electronic structure and bonding in the {FeNO}6 species.

Main Methods:

• Synthesis of mononuclear nonheme iron(iii)-nitrito and {FeNO}6 complexes with a TAML ligand.
• Spectroscopic characterization including 1H nuclear magnetic resonance and X-ray absorption spectroscopy.
• Computational studies to support structural and electronic assignments.
• Exploration of alternative synthetic pathways: protonation-triggered reduction and photochemical reduction.

Main Results:

• Successful synthesis and characterization of [(TAML)FeIII(NO)]- ({FeNO}6) and [(TAML)FeIII(NO2)]2- (iron(iii)-nitrito) complexes.
• Spectroscopic and computational data indicate a neutral nitric oxide ligand and a diamagnetic Fe center (S = 0) in the {FeNO}6 complex.
• Demonstration of alternative synthetic routes, including a novel photochemical nitrite reduction in a nonheme iron model.

Conclusions:

• The study provides a comprehensive characterization of a nonheme {FeNO}6 complex, clarifying its electronic structure.
• Novel synthetic pathways, including photochemical reduction, were established for generating iron-nitrosyl species.
• This work contributes to a deeper understanding of nonheme iron-nitric oxide chemistry and opens new avenues for its synthesis.