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*Dy-2{-(OC)(2)FeCp}](2) (1(Dy)), 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 662cm(-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.