Nitrosyl Iron Complexes in Biological and Chemical Systems

Nitrosyl iron complexes represent a versatile class of coordination compounds in which nitric oxide (NO) is bound to iron centres, often forming mononuclear or dinuclear species. In biology, these complexes serve as transient carriers and reservoirs for NO, mediating vasodilation, neurotransmission and cytoprotective signalling. Dinitrosyl iron complexes (DNICs) arise naturally through the interaction of NO with labile iron pools or iron–sulfur clusters, influencing redox homeostasis and gene regulation under nitrosative stress. In synthetic chemistry, nitrosyl iron complexes are exploited as spin probes, magnetic materials and catalysts, their electronic structures finely tunable by ancillary ligands such as thiolates, phenoxides or multidentate donors. Advances in spectroscopic methods—electron paramagnetic resonance (EPR), infrared vibrational analysis and X-ray crystallography—have illuminated the electronic delocalisation between NO ligands and iron centres, revealing redox non-innocence and ligand-based storage of unpaired electrons. The capacity of nitrosyl iron complexes to release NO or nitrosonium equivalents under controlled conditions underpins emerging applications in targeted drug delivery, regenerative medicine and molecular electronics. Cross-disciplinary studies continue to bridge mechanistic insights from enzyme nitrosylation to the design of heterobimetallic frameworks, emphasising global significance in health, environmental sensing and advanced materials.

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Nitrosyl Iron Complexes in Biological and Chemical Systems publication trend

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Technical terms

Dinitrosyl iron complex (DNIC): A coordination species with two NO ligands bound to one or two iron centres, often paramagnetic and biologically relevant for NO storage.

Nitrosyl ligand: The NO group bound to a metal centre, which can exist in multiple redox forms (NO⁺, NO·, NO⁻) and modulate electronic structure.

Thiolate ligand: A sulphur-containing donor (RS–) that binds metals, stabilising certain redox states and influencing spin coupling.

Paramagnetism: A form of magnetism arising from unpaired electrons in a complex that respond weakly to external magnetic fields, often probed by EPR.

References

1. Mechanistic and Kinetic Insights into Cellular Uptake of Biomimetic Dinitrosyl Iron Complexes and Intracellular Delivery of NO for Activation of Cytoprotective HO‑1. JACS Au (2024).
2. Binding of a single nitric oxide molecule is sufficient to disrupt DNA binding of the nitrosative stress regulator NsrR. Chemical Science (2024).
3. Electronic Structure and Transformation of Dinitrosyl Iron Complexes (DNICs) Regulated by Redox Non-Innocent Imino-Substituted Phenoxide Ligand. Inorganic Chemistry (2024).