Synthesis, structures, and magnetic properties of three fluoride-bridged lanthanide compounds: effect of bridging fluoride ions on magnetic behaviors

A family of fluoride-bridged lanthanide compounds, [Dy(III)F(oda)(H(2)O)(3)] (1, oda = oxidiacetate) and [Ln(III)(2)F(2)(oda)(2)(H(2)O)(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 [Ln(III)(2)(OH)(2)(oda)(2)(H(2)O)(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 Dy(2) 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.