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* 2 Dyμ‐(OC) 2 FeCp] 2 ( 1 Dy ), which contains a rhombus‐shaped Dy 2 Fe 2 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 1 Dy involves at least the fourth‐excited Kramers doublet, thus demonstrating that prominent SMM behavior can be observed for dysprosium in low‐symmetry environments.