Slow magnetic relaxation of a mononuclear dysprosium complex derived from 4,4,4-trifluoro-1-(2-naphthyl)-1,3-butanedione and 1,10-phenanthroline

Two mononuclear complexes, [(tfnb) 3 Ln(phen)] (Ln = Tb or Dy, tfnb = 4,4,4-trifluoro-1-(2-naphthyl)-1,3-butanedione, phen = 1,10-phenanthroline), were isolated and structurally determined using single crystal X-ray diffraction techniques. The crystallographic data reveal that the two complexes are isostructural and adopt a trigonal dodecahedral geometry. The dysprosium complex exhibits a slow relaxation of the magnetization in the absence of a dc field. A combination of QTM, Raman and Orbach processes was considered in energy barrier fitting, giving the effective barrier U eff = 193 K. The magnetic easy axis calculated using an electrostatic model follows the direction of the two tfnb − ligands in the trans position. A mononuclear dysprosium complex with a triangular dodecahedron geometry behaves as a single-molecule magnet with the effective barrier U eff = 193 K.