Iron complexes with gallic acid: a computational study on coordination compounds of interest for the preservation of cultural heritage

Abstract

The electronic structures of iron coordination compounds [FeL4H12]−, [FeL4H12]2−, [Fe3L8H22]−, and [Fe3L8H22]2− (H4L = gallic acid, 3,4,5-trihydroxybenzoic acid) have been studied by density functional theory calculations, together with the 1-D periodic complex [Fe3L6H15]∞. Data regarding the ground-state spin multiplicities of these models for iron gall inks, the charge and spin distributions, the oxidation states of the metal centers, and the oxidizing potentials of the complexes have been computed. The absorption properties of these compounds have been related to the electronic structure of the coordinated ligands.