Anion-dependent dysprosium(III) cluster single-molecule magnets.

A new Schiff base ligand, which is formed by the condensation reaction of 5-fluorosalicylaldehyde and pyrimidine-4-carbonyl hydrazide {H2LSchiff = (E)-N′-(5-fluoro-2-hydroxybenzylidene)pyrimidine-4-carbohydrazide}, was made to react with different dysprosium(III) salts in an alkaline solution to assemble Dy4 and Dy6 cluster complexes, [Dy4(OH)2(LSchiff)4(H2O)2(NO3)2]·4MeCN·MeOH (1) and [Dy6(CO3)2(LSchiff)6(H2O)3(MeOH)Cl2]·5MeOH (2), depending on whether the anion used is nitrate or chloride. Complex 1 corresponding to the nitrate anion is a butterfly-like Dy4 cluster complex with four different Dy(III) coordination configurations of [O6N2], [O8N], [O7N2] and [O6N3]; when the anion is replaced by the chloride anion, carbon dioxide can be automatically captured from the air and converted into a carbonate bridging ligand, and the final product obtained is complex 2, which is a triangular prism-type Dy6 cluster complex with double μ3-carbonate bridging ligands. Both 1 and 2 show good zero-field SMM properties, with Ueff/k values of 116.5 K for 1 and 150.9 K for 2. [ABSTRACT FROM AUTHOR]