Synthesis, Structures, and Magnetic Properties of Three Fluoride-Bridged Lanthanide Compounds: Effect of Bridging Fluoride Ions on Magnetic Behaviors

摘要

A family of fluoride-bridged lanthanide compounds, [DyIIIF(oda)(H2O)3] (1, oda = oxidiacetate) and [LnIII2F2(oda)2(H2O)2] (Ln = Tb(2) and Dy(3)), was synthesized and characterized. To investigate the effects of bridging ligands on magnetic behaviors, two hydroxyl-bridged complexes of formulas [LnIII2(OH)2(oda)2(H2O)4] (Ln = Tb(4) and Dy(5)) were also synthesized. Magnetic measurements show that the magnetic behaviors of the compounds are obviously distinct. Compounds 1, 2, and 3 show ferromagnetic interactions, while only antiferromagnetic interactions are observed in compounds 4 and 5. Among these compounds, 1 and 3 show frequency-dependent ac-susceptibility indicative of slow magnetic relaxation. Because the structures of Dy2 cores are very similar in compounds 3 and 5, it may be inferred that the differences of bridging ligands are mainly responsible for the distinct magnetic exchange interactions and relaxation dynamics.