Abstract: This report describes how the coordination of FeCl2 with tris(pyridin-2-ylmethyl)amine (TPA) ligands offers the possibilty to activate the molecular dioxygen in biomimetic processes. . It includes all procedures taken to the case for major oxidation reactions carried out in Nature under particular conditions. The aim of the this paper is to present the outcome of a thorough study for complex coordinations with ligands substituted by groups known as electron donors. It demonstrates how ligands with methoxy substituents are likely to be demethylated, and therefore providing entities potentially useful in synthesis. Targeting in modulating the electronic properties at the metal center, a new type of ligand (MeO)2TPA has been prepared and the complex of (MeO)2TPAFeCl2 has been studied by uv-visble ; 1H RMN paramagnatic and conductometry. The effect of (MeO) group in α-substituted on the structure as well as the effect of substitution on the oxygenation of the complex has been verified. Afterwards, the reactivity of the complex towards molecular dioxygen in absence of substrat is checked by uv-visble, 1H RMN paramagnatic and radiocristallography. As well, the reactivity in presence of substrat is tested.