Complexes containing trivalent lanthanide ions are of great interest in molecular magnetism. They can give rise to SMM with slow magnetic relaxation, uniaxial magnetic anisotropy and high-energy barrier to the reversal of the magnetic moment. These features originate from the subtle interplay between the spin-orbit coupling and the crystal field interaction created by the ligands surrounding the lanthanide ion. Few general rules for building SMM have been formulated but no fundamental magneto-structural relationship explaining the behavior of lanthanide-based SMM has been proposed yet .
To this end, and in addition to experimental evidences (SQUID magnetometry, EPR spectroscopy, polarized neutron diffraction…) ab initio calculations (SA-CASSCF/PT2/SISO) are one of the most appropriate theoretical tools to get reliable insights into the electronic structure of these compounds. Herein, the recent elucidation of the magnetic behavior of several lanthanide-based complexes is reported . The limits of this computational approach is discussed.
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