High-Coordinated Dy₂ Single-Molecule Magnet with an Anistropy Barrier Exceeding 700 K

We report the synthesis and characterization of a symmetric dinucler Dy-III complex (1) based on the use of bulk pentapyridyldiamine (BPA-TPA) and bridging hydroquinone ligands. Each Dy-III ion is wrapped by a BPA-TPA ligand, leaving only one site to bond one O donor atom from the hydroquinone, which generates a triangular dodecahedral coordinate geometry. Magnetic measurements reveal that complex 1 exhibits a high anistropy barrier of 727(4) K and the temperature of hysteresis loops up to 20 K with remanence at the zero field. However, the Y(III)-diluted analogue 1@Y shows that butterfly-shaped hysteresis loops are closed at the zero field. This discrepancy clearly demonstrates the positive effect of axial magnetic interaction between the Dy-III dimer. The fascinating behavior is ascribed to the pseudolinear ligand field with an exceptionally short Dy-O bond, as confirmed by theoretical calculations