MonoOxygenases (MO) such as cytochromes P450 catalyse the oxygen atom insertion into a chemical bond of an inert organic substrate following reductive activation of dioxygen. By using very simple Fe(II) complexes bearing amine/pyridine ligands, it is possible to prepare reactive species such as Fe(III)OOH and Fe(IV)O by using chemical oxidants (H2O2, peroxides, peracides...), or O2 in the presence of a chemical reductant via a reaction sequence similar to the one of P450. These intermediates have shown an efficient activity on hydroxylation of aromatic, and oxydation of olefins and alkanes. Nevertheless, these reactions suffer from a lack of specificity and regioselectivity. A drawback to the use of these complexes in oxidation catalysis by O2 is the side reaction between the oxidative intermediate species and the chemical reductant used. To solve these problems, different approaches have been developed during this thesis, in view to better mimic enzymes activity, and reproduce oxidation reactions efficiency and selectivity.A first strategy is to add an artificial cavity (calix[6]aren) to our iron complexes. A study of the catalytic site, bearing a triazole function resulting from the “click” chemistry, have been followed. The synthesis of a new iron-zinc complex have been then realized, with the insertion of the two metals in their destined coordination site was controlled. Insertion of a substrate inside the cavity has been realized, forming a system which could improve selectivity and efficiency of alkanes oxidation reactions.The second strategy developed was to use an electrode as source of electrons, during activation of O2 by an iron(II) complex. The cyclic voltammetry study of this reaction allowed us to reveal the formation of an adduct FeII-O2 in reductive conditions. An intermediate FeIII-peroxo was then detected at the electrode in oxidation, which generates a species with a high oxidation degree. This intermediate, generated in solution directly by reaction with H2O2, could realize oxidation reactions in oxidative conditions. New electrocatalytical systems could be then developed.
