The Coordination Chemistry of Nitric Oxide with Pentacyanoferrates

Recent advances in the coordination chemistry studies of the redox-interconverted ligands NO, NO and NO(HNO), particularly related to the pentacyanoferrate(II) and (III) fragments, are summarized with mention of structural, spectroscopic (IR and EPR) and DFT calculations. The chemistry of bound NO is presented with an emphasis on the mechanisms of the nucleophilic addition reactions of OH, amines and thiolates on the nitroprusside ion (NP). The reactions of nitric oxide, NO, are addressed through the mechanistic analysis of the formation and dissociation reactions of the [Fe(CN) 5 NO] complex, and through its redox reaction with the [Fe(CN) 5 H 2 O] ion, leading to NP. Other biologically significant issues related to the reactivity of bound NO are analysed, namely the disproportionation reactions, the role of dinitrosyls and the identity of nitroxyl, HNO, as a theoretically characterized reduced species, which seemingly appears as an intermediate in redox reactions of small nitrogenated molecules.