Mössbauer Study of Irradiated Iron Chelates and Chemical Consequences of 57Co Electron Capture in Complex Ligand Compounds

Abstract

The Mössbauer absorption spectra of Fe(III) acetylacetonate, Fe(III) citrate Fe(III) EDTA and Fe(III) trisdipyperidyl perchlorate irradiated with electrons at liquid nitrogen temperature are found to be similar to the emission spectra after electron capture of 57Co in analogous Co(III) compounds. This result suggests that an autoradiolysis mechanism is responsible for the stabilization of the anomalous iron charge states in these compounds. The main effect of the radiolysis is found to be the reduction of the trivalent iron complex to the corresponding bivalent one. A mechanism involving the formation and fast annihilation of free radicals is invoked for explaining the radiation reduction process.