The Single-Molecule Magnets (SMMs) are polymetallic complexes containing unpaired electrons that have the remarkable property to behave individually as magnets. Synthesized according to the methods of coordination chemistry they have become the subject of intense multidisciplinary research at the interface of chemistry and physics. In this context our thesis was focused on the synthesis of several series of new polynuclear complexes and their characterization by X-ray diffraction and magnetic measurements. The obtained results are discussed in this manuscript. The first chapter presents the theoretical approach and scientific advances in the field of molecular magnets. The second chapter describes the coordination compounds obtained using the oxime-based ligands: two homonuclear complexes, [Mn3]n and [Mn6], and two heteronuclear series, [Ln2Cu2] and [Ln3Cu8] (LnIII = Dy, Gd, Tb, Y). According to the magnetic studies [Mn3]n, [Dy2Cu2] and [Dy3Cu8] behave as SMM. The third chapter is related to a tetranuclear [Mn4] cluster and a series of dodecanuclear benzoxazoles-based complexes [Ln4Cu8] (LnIII = Dy, Gd, Y). The magnetic measurements made on [Dy4Cu8] showed the characteristic behavior of a SMM. The final chapter presents a valence-mixed MnII - MnIII [Mn14] complex with ferromagnetic and antiferromagnetic interactions between manganese ions obtained using a Schiff base ligand. To conclude the main obtained results will be discussed and some perspectives opened by our work will be proposed.
Molecular magnets based on polymetallic clusters : synthesis, crystal structures and magnetic properties