Every year, the SCF regional office rewards promising young scientists for the work they have carried out during their doctorate.
The first part of this work focuses on the dehydrogenation of alkanes to alkenes. Our approach is based on the use of polyoxometallate hybrids decorated with silanol functions (SiloxPOMs), which are relevant molecular models of unique sites on silicic surfaces. Our approach is to combine in a single system the ability of the polyoxotungstic structure to carry out hydrogen atom transfer under UV irradiation, in tandem with a metal cation promoting H2 formation. The various studies carried out highlighted the formation of reduced and protonated species, identified by NMR and UV-Vis. The second part of this thesis focuses on the decomposition of hydrogen peroxide on titanium-SiloxPOM complexes. Kinetic studies have enabled us to identify the factors favouring this decomposition (temperature, role of water and steric hindrance). In addition, the nuclearity of the species formed on addition of H2O2 was demonstrated by 1H DOSY. The radical species identified by EPR and preliminary theoretical calculations enabled us to propose a probable mechanism involving the formation of an original reaction intermediate, Ti-trioxidane (Ti-OOOH).