IRON COMPLEXES OF THE SCHIFF-BASE LIGAND BIS(2,5-DIHYDROXYACETO-PHENONE)ETHYLENEDIAMINE

Iron complexes of the tetradentate ligand, bis(2,5-dihydroxyacetopheno ne)ethylenediamine, and a fifth anionic ligand have been prepared and characterized by spectroscopic techniques. E.p.r. studies of the X-ban d frozen DMF solution reveal the presence of a broad, g ca. 4.0, signa l with weak features at lower fields. The complexes exhibit a broad vi sible band with lambda(max) in the 550-605 nm range which is assigned to the phenolate --> Fe charge transfer transition. The LMCT band ener gy 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.