Reaction of nitrogen dioxide with iron tetraphenylporphyrinate nitro complex containing the trans-1-methylimidazole ligand

Abstract

Electron and IR spectroscopy, as well as the data on the isotopic analog 15NO2, were used for the studies of the reaction of nitrogen dioxide (NO2) with thin layers of the six-coordinated FeIII-porphyrin nitro complex with trans-1-methylimidazole ligand Fe(TPP)(1-MeIm)(NO2) (TPP is the meso-tetraphenylporphyrinate dianion), which is a heme-modelling system. It was shown that, like in the case of the five-coordinated nitrite complex, additional portions of NO2 promote the nitrite-to-nitrate transformation, accompanied by the evolution of NO. The reaction leads to the formation in the layer of five- and six-coordinated Fe-porphyrin nitrate complexes and a small amount of imidazole complexes FeIII(TPP)(1-MeIm)2 with the outersphere nitrate anion. The latter complex became predominate after treatment of this layer with additional portion of 1-methylimidazole.