Synthesis, Structure, and Magnetic Properties of a Series of Dinuclear Lanthanide Complexes Assembled by Acetate and a Schiff Base Ligand

Five dinuclear lanthanide complexes [Ln(2)L(2)(NO3)(2)(OAc)(4)]center dot 2CH(3)CN [Ln = Gd (1), Tb (2), Dy (3), Ho (4), and Er (5)] [L = 2(( 2-pyridinylmethylene) hydrazine) ethanol] were synthesized from the reactions of Ln(NO3)(3)center dot 6H(2)O with L and CH3COOH in the presence of triethylamine. Their crystal structures were determined. They show similar dinuclear cores with the two lanthanide ions bridged by four acetate ligands in the mu(2)-eta(1):eta(2) and mu(2)-eta(1):eta(1) bridging modes. Each Ln(III) ion in complexes 1-5 is further chelated by one L ligand and one nitrate ion, leading to the formation of a nine-coordinated monocapped square antiprism arrangement. The dinuclear molecules in 1-5 are consolidated by hydrogen bonds and pi center dot center dot center dot pi stacking interactions to build a two-dimensional sheet. Their magnetic properties were investigated. It revealed antiferromagnetic interactions between the Gd-III ions in 1 and ferromagnetic interactions between the Tb-III ions in 2. The profiles of chi T-m vs. T curves of 3-5 reveal that the magnetic properties of 3-5 are probably dominated by the thermal depopulation of the Stark sublevels of Ln(III) ions.