A low-symmetry dysprosium metallocene single-molecule magnet with a high anisotropy barrier

The single-molecule magnet (SMM) properties of the isocarbonyl-ligated dysprosium metallocene [Cp*2Dy- {m-(OC)2FeCp}]2 (1Dy), which contains a rhombus-shaped Dy2Fe2 core, are described. Combining a strong axial [Cp*]¢ ligand field with a weak equatorial field consisting of the isocarbonyl ligands leads to an anisotropy barrier of 662 cm¢1 in zero applied field. The dominant thermal relaxation pathways in 1Dy involves at least the fourth-excited Kramers doublet, thus demonstrating that prominent SMM behavior can be observed for dysprosium in low-symmetry environments.