A stable hyponitrite-bridged iron porphyrin complex

Area of Science:

• Bioinorganic Chemistry
• Organometallic Chemistry

Background:

• Nitric oxide (NO) conversion to nitrous oxide (N2O) by heme enzymes involves heme-Fe{N2O2}(n-) intermediates.
• Previous studies proposed formulations for these intermediates, but lacked structural evidence.

Purpose of the Study:

• To isolate and characterize a stable heme-Fe{N2O2}(n-) complex.
• To provide structural insights into NO coupling mechanisms in heme active sites.

Main Methods:

• Synthesis of a stable bimetallic hyponitrite iron porphyrin, [(OEP)Fe]2(μ-N2O2), from [(OEP)Fe]2(μ-O) and hyponitrous acid.
• Characterization using spectroscopic and analytical techniques.
• Density functional theoretical (DFT) calculations on a model compound [(porphine)Fe]2(μ-N2O2) to elucidate electronic structure.

Main Results:

• Successful isolation and characterization of the first stable bimetallic hyponitrite iron porphyrin complex.
• Structural and electronic properties of the complex were determined.
• DFT calculations provided insights into the electronic structure and bonding of the hyponitrite ligand.

Conclusions:

• The reported complex represents a key intermediate in NO metabolism by heme enzymes.
• This work provides crucial structural data for understanding the mechanism of N2O formation.
• The findings open new avenues for designing catalysts for nitrogen oxide conversions.