Oxidation reactions are one of the most important chemical transformations applied both in bulk and fine chemistry. In nature, this type of reactions is catalyzed by metalloenzymes which can perform highly selective transformations under mild conditions. Several bioinspired model systems have been developed but key issues remain to be successfully developed both from the catalysis point of view and also from the fundamental understanding of key reaction intermediates. In this project, we will tackle two of these topics.Activation of N2O with first-row transition-metals: nitrous oxide (N2O) is a greenhouse gas but it also constitutes an environmentally friendly alternative to the traditional oxidants used nowadays as it only generates N2 as waste. Despite being thermodynamically a potent oxidant, N2O is kinetically very stable. However, these kinetic barriers can be overcome through activation by suitable metal centers. In the present proposal we will activate N2O with mononuclear first-row transition metal complexes. The prospective species derived from this process will be used as oxidants for the selective oxidation of organic substrates.Fe-Ni heterobimetallic systems involved in O2 activation: heterobimetallic-O2 intermediates are of interest due to the possible “synergistic” effect of two different metal ions acting together. In addition, O2 activation at heterobimetallic complexes will result in novel chemical species distinct from homometallic species, and therefore they will exhibit new oxidation reactivity patterns that could eventually translate into novel selectivity. Here, we pursue the synthesis of heterobimetallic complexes involved in O2 activation combining iron and nickel. These species are prepared by reaction of a well-characterized and thermally stable nickel-O2 complex with iron(II) metal complexes. Although the reactivity of both independent components is already known, their synergistic action is envisioned to lead unprecedented reactivity