A Nonheme, High-Spin {FeNO}⁸ Complex that Spontaneously Generates N₂O

Area of Science:

• Bioinorganic Chemistry
• Organometallic Chemistry
• Enzyme Mechanisms

Background:

• Nonheme iron-nitrosyl complexes are crucial in biological systems.
• Understanding nitric oxide reductases (NORs) is vital for nitrogen cycling and bioenergetics.
• Previous studies have focused on heme-containing NORs, leaving nonheme systems less explored.

Purpose of the Study:

• To synthesize and characterize a novel nonheme {FeNO}⁸ complex.
• To investigate the reactivity and N₂O generation of this complex.
• To elucidate potential mechanisms relevant to nonheme nitric oxide reductases.

Main Methods:

• One-electron reduction of a precursor iron-nitrosyl complex ([Fe(NO)-(N3PyS)]BF₄).
• Synthesis of the target complex via addition of Piloty's acid (an HNO donor) to an Fe^II precursor.
• Characterization of the resulting nonheme {FeNO}⁸ species.

Main Results:

• A metastable nonheme {FeNO}⁸ complex, [Fe(NO)(N3PyS)], was successfully produced.
• This complex is a rare example of a high-spin (S=1) {FeNO}⁸ species.
• It is the first reported mononuclear nonheme {FeNO}⁸ complex capable of generating N₂O.

Conclusions:

• The study presents a novel nonheme {FeNO}⁸ complex with unique reactivity.
• The generation of N₂O from this complex provides insights into NOR mechanisms.
• This work opens new avenues for studying nonheme iron-containing enzymes involved in NO metabolism.