It has been reported that the organic-soluble porphyrin complex [Fe^III(OEP)Cl] (OEP = octaethyl porphyrin) and potassium crown-ether nitrite can serve as selective oxygen atom transfer (OAT) agents to various organic substrates.  We are studying the mechanism of this reaction and related OAT reactions involving nitrite mediated by both organic and water soluble metal centers.  The reaction has been proposed to proceed through iron-nitro (FeNO₂) intermediate complex.  One logical mechanism would be for OAT to occur from a ferric nitro complex (Fe^III-NO₂) giving an Fe^IINO product.  Alternatively, the reaction could proceed via the intermediates of nitrogen dioxide generated from the nitrite.  Studies of the reaction of Fe^II(TPP) (TPP = tetraphenyl porphyrin) with NO₂ in layered solids give the 5-coordinate nitrito complex Fe(TPP)(ONO), however this isomerizes to give a nitro complex upon coordination of a sixth ligand.²  Mechanistic and kinetic studies on nitrite reactions with heme models relevant to such OAT will be presented.