Slow Magnetic Relaxation in a Double-Decker Dy(III) Single-Molecule Magnet

Two novel double-decker 3d–4f complexes with the general formula [Ln2Cu10(OH)2(quinha)10(py)12](CF3SO3)4·2py·6CH3OH·4H2O (Ln = Dy (1); Ln = Y (2)) have been synthesized and characterized. Single X-ray diffraction showed that each Ln ion is located in the center of a rigid and planar Cu5 metallacrown (MC) with pseudo D2d symmetry. Two Ln[15-MCCu-5] units are connected by two OH– bridges to form a central symmetric double-decker complex 1. Magnetic studies have revealed the presence of ferromagnetic DyIII–DyIII coupling and zero-field single-molecule magnet (SMM) behavior in 1. In contrast, 2 does not exhibit slow magnetic relaxation even when a dc magnetic field is applied. Combined with theoretical calculations, the quantum tunneling of magnetization (QTM) in 1 is partially suppressed, which may be caused by the Dy–Dy interaction.