DFT study on the reactivity of iron porphyrins tuned by ring substitution

D.E. BIKIEL; S.E. BARI; F. DOCTOROVICH; D.A. ESTRIN

JOURNAL OF INORGANIC BIOCHEMISTRY

Wiley

Año: 2008 vol. 102 p. 70 - 76

0162-0134

    The effect of b-substituents (–NO2, –Br, –OCH3) in the reactivity of Fe(II) and Fe(III) porphyrins is studied by means of density func-ional theory (DFT) calculations. The binding of nitric oxide, carbon monoxide and dioxygen (NO, CO, O2) was explored due to therelevance of their interactions in the chemistry of heme proteins and in biomimetic catalysis. The binding capability (BC) of the porphy-rins was found to be strongly modulated both by the donor and attractor substituents used in the work. Unexpectedly, we found that theBC of Fe(II) porphyrins is mainly decreased for the diatomic ligands, when both donor or withdrawing substituents were considered.This effect was particularly significant when the ligand was oxygen. The correlation of Fe–X and X–O (X = N, C, O) bond distancesis explained in terms of backdonation effects.