The objective of this project is to synthesize heterometallic complexes combining an organolanthanide fragment, a redox non-innocent ligand and a reactive transition metal fragment. The final goal is C-H bonds activation and olefins transformation. Since the beginning of the project, we have been able to synthesize such challenging heterometallic complexes with divalent ytterbium, samarium and thulium fragments, six different redox non-innocent ligands and group 10 transition metals (Ni, Pd, Pt). All synthetic details have been investigated and the adapted conditions for their synthesis have been well worked out. All the complexes have been characterized with routine characterization means, such as 1H NMR of paramagnetic compounds, UV-Visible absorption, X-ray diffraction studies as well as specific experimental characterization such as magnetism and Electron Paramagnetic Resonance (EPR) spectroscopy. Several complexes were also studied by theoretical computations at different levels. Methods for electronic density analysis have been used. All these experimental and theoretical methods have allowed specifying the electronic structure of these complexes and showed that the divalent lanthanide fragments, the redox non-innocent ligands as well as the transition metal fragments are all responsible for modification the nature of the ground and first excited states, so that it is possible to tune them at will, a rare opportunity in organometallic chemistry. Stoichiometric reactions have been performed on these heterometallic complexes with oxidants and small pollutant molecules (CO). Important results have been obtained such as the isolation of high-valent palladium and platinum species, and insertion of carbon monoxide in Ni-C bonds and alkene isomerization with simple nickel complexes while the Pd(IV) chemistry has expended. Additionally, very interesting magnetic properties have been observed for low-valent complexes of thulium and outstanding reactivity of similar low-valent thulium complexes have been discovered with CO. 8 articles including one in the Journal of American Chemical Society and one in Angewandte Chemie have been published so far and several other are submitted or in preparation. Over the period, the team has been involved in 40 disseminations in many different countries, for the scientific community (participation to conferences, invitation in workshop or in seminars) but also the general public (article, video, general public conference).