Solid-state structures of metalloporphyrin NOx compounds

A comprehensive summary of the salient stereochemical features of the small molecule metalloporphyrin derivatives with nitric oxide, nitrite, and nitrate as axial ligands is presented. It is shown that there are structural expectation values for each metal ion, its oxidation level, and axial ligand. Some possible nuances are also apparent. The unequaled variety displayed by the iron derivatives, commensurate with their biological functions, is clear and consistent with their heme protein role as redox catalysts and gas carriers/sensors. Iron derivatives alone significantly utilize more than one oxidation state and display a variety of structural types.