How Far can the Anisotropy Deviate from Uniaxiality in a Dy-Based Single-Molecule Magnet? Dinuclear Dy(III) Complex Study

Abstract

The Dy^III ions in the dimer [Dy₂(H₂tea)₂(O₂CPh)₄]·2H₂O (1) (H₃tea = triethanolamine) have the 9-coordinate monocapped square-antiprismatic ligand field environment. Compound 1 shows slow relaxation of magnetization which is observable only with applied magnetic fields. This is consistent with the idea that low-symmetry ligand fields allow for the quantum tunneling of magnetization. This is reflected by the fact that there are no observable maxima in the out-of-phase ac susceptibility above 1.8 K. The {g}-tensor of the Dy^III ions {g_x = 11, g_y = 8.2, g_z = 1} further underlying the reduced uniaxiality in this system was determined in electron paramagnetic resonance (X- and Q-band) studies of 1 at temperatures down to 4 K.