Electronic effects of electron-donating and withdrawing groups in model complexes for iron-tyrosine-containing metalloenzyme

Three new iron(III) complexes with the ligand N,N'-bis(2-hydroxybenzyl)-N-N'-bis(pyridine-2-ylmethyl)ethylenediamine, H9sub 2)bbpen, containing electron-donating and withdrawing groups (me, Br, NO(sub 2) in the 5-position of phenol rings were synthesized and characterized. The redox potentials Fe(super III)/Fe(super II) and the energies of the charge transfer process of these complexes were found to be linearly correlated with the Hammett parameter.