EPR and NMR studies of Fe(I)-NO complexes and their relevance in biological and environmental processes

Nitric oxide is implicated in a wide range of biological functions and in many processes of ecological importance. The formation of iron–nitrosyl complexes is fairly well documented, although the oxidation state of the iron atom is not adequately elucidated: the metal ion is in the formal +1 oxidation state forming low- and high-spin d7 complexes. Owing to the documented evidence that iron–NO compounds are involved in bioregulatory mechanisms and immune responses, and to the biological relevance of these processes and of related structures, the EPR and NMR features of these complexes were reconsidered and combined EPR and NMR analysis was carried out to obtain information on binding sites and coordination behaviour.