Slow Magnetic Relaxation in Mononuclear Octahedral Manganese(III) Complexes with Dibenzoylmethanide Ligands

The structural characterization and magnetic studies of three mononuclear MnIII complexes based on the dibenzoylmethanido (dbm–) ligand, Mn(dbm)3 (1) and [Mn(dbm)2(L)2](ClO4) (L = dimethyl sulfoxide, 2; L = pyridine, 3), are reported. The MnIII ions are in an axially elongated octahedral coordination geometry. The axial zero‐field‐splitting parameters D, ranging from –3.42 to –4.52 cm–1 for the three complexes, were obtained by fitting magnetic‐susceptibility and magnetization data. Ab initio calculations also show the axial magnetic anisotropy in the molecules of 1–3. With an applied dc field, the ac susceptibility measurements reveal slow magnetic relaxation in 1–3. The possible relationship between the structures and the magnetic properties in these complexes are discussed.