A slowly magnetic relaxing SmIII monomer with a D5h equatorial compressed ligand field

Abstract

By using a bi-dentate phosphine oxide ligand L (L = bis(diphenylphosphino)methane dioxide), two mono-nuclear lanthanide complexes [LnL₂(DMF)Cl₂]Cl (Ln = Sm, 1; Dy, 2) with a D_5h equatorial ligand field (LF) are obtained. Ab initio CASSCF calculations suggest that the equatorial LF promotes the magnetic anisotropy of the central Sm^III and impair that of Dy^III. Alternating current (ac) susceptibility measurements reveal that the samarium complex is the first Sm^III mono-nuclear complex with slow magnetic relaxation. The isostructural Dy^III compound, in contrast, relaxes much faster. Further magnetic property studies were then performed to probe the origin of magnetic anisotropy and magnetic relaxations.