SPECTROSCOPIC AND ELECTROREDUCTIVE CHARACTERIZATION OF NEW MU-OXO-DIIRON(III) COMPOUNDS WITH ACYCLIC TETRADENTATE LIGANDS

We report the FT-i.r., FT-Raman, electronic, and Mossbauer spectra for several new mu-oxo-monobridge (FeOFeIII)-O-III compounds with acyclic tetradentate ligands. Mossbauer spectra confirm the oxidation states for these complexes. The symmetric and asymmetric stretching frequenci es determined for Fe-O-Fe bonds have allowed changes to be predicted i n the M-O-M angle (from 144.6 to 150.7 degrees). The electronic absorp tion spectra surprisingly resemble features exhibited by the spectrum of hemerythrine. Voltammetric results in DMF with a vitreous carbon el ectrode reveal three one-electron reduction stages which correspond to the dimeric processes Fe-III Fe-III/Fe-II Fe-III and Fe-II Fe-III/Fe- II Fe-II, and to the monomeric process Fe-II/Fe-I.