Iron complexes of the Schiff base ligand bis(2,5-dihydroxyacetophenone) ethylenediamine

Abstract

Iron complexes of the tetradentate ligand, bis(2,5-dihydroxyacetophenone) ethylenediamine, and a fifth anionic ligand have been prepared and characterized by spectroscopic techniques. E.p.r. studies of the X-band frozen DMF solution reveal the presence of a broad, g ca. 4.0, signal with weak features at lower fields. The complexes exhibit a broad visible band with λmax in the 550–605 nm range which is assigned to the phenolate → Fe charge transfer transition. The LMCT band energy varies with the anionic ligand, namely, N3-> Bz- > HCOO- > Cl- > ClO4-(Bz- = benzimidazole anion), similar to the behaviour of dioxygenases and proteins containing tyrosine coordinated to iron.