Electrochemistry and spectroscopy of sulfate and thiosulfate complexes of iron porphyrins

Abstract

Abstract:The electrochemical and spectroscopic properties of the complex formed by the addition of thiosulfate to ferric porphyrins were examined. The NMR spectrum of the thiosulfate-ferric porphyrin complex was consistent with a high-spin ferric complex, while the EPR spectrum at liquid nitrogen temperatures indicated that the complex under these conditions was low-spin. Such behavior has been previously observed for other ferric-porphyrin complexes. The visible spectra were characterized by a shift in the Soret band to higher energies, with smaller changes in the longer wavelength region. The complex was reasonably stable in DMF, but slowly reduced over several hours to Fe II (TPP) and S4O6 2-. The voltammetric behavior of the thiosulfate complex in DMF consists of two waves, the first of which was irreversible. The

Electrochemistry and Spectroscopy of Sulfate Complexes of (Tetraphenylporphyrinato)manganese

“…The iron analog, [Fe 2 -(tpp) 2 (SO 4 )], has been shown to be stable only in non-coordinating solvents [5]. In coordinating solvents and in the presence of excess sulfate, the iron derivative dissociates [5] [6]. The behavior of [Mn 2 (tpp) 2 SO 4 ] will, therefore, be compared to that of the corresponding iron derivative under similar conditions.…”