Magnetic Anisotropy and Quantum Tunneling of Magnetizations in Two Isomorphic Dy(III) Complexes

Two Dy(III) single-ion magnets, formulated as [Dy(Mbpen)(OPhNO2NH2Cl)2X]·C2H5OH (X = Cl for 1, Br for 2), were synthesized using N,N′-dimethyl-N,N′-bis(2-pyridylmethyl)ethylenediamine (Mbpen) and 2-amino-6-chloro-4-nitrophenol(ClNH2NO2PhOH) in combination with different dysprosium halides. X-ray crystallographic studies demonstrate that complexes 1 and 2 adopt isomorphic mononuclear structures, wherein the Dy(III) ion exhibits eight-coordination within a geometrically similar triangular-dodecahedral N5O2X ligand field. Magnetic studies indicate that both 1 and 2 are zero-field, single-ion magnets and display observable low-temperature hysteresis. High-level ab initio calculations were conducted to explain the characteristics of the low-lying energy levels in the target complexes. Furthermore, the magnetic anisotropy and quantum tunneling of magnetization are interpreted via the crystal field model.