Effect of coordinated anions on ferromagnetically coupled Dy2 zero-field single-molecule magnets

Abstract

A new hydrazone Schiff base ligand was condensed from 2-hydroxy-3-methoxybenzaldehyde and pyrimidine-4-carbohydrazide {H₂L = (E)-N′-(2-hydroxy-3-methoxybenzylidene)pyrimidine-4-carbohydrazide}, which was used to assemble two new Dy₂ complexes Dy₂L₂(DMF)₂(NO₃)₂ (1) and Dy₂L₂(DMF)₂(AcO)₂ (2). Notably, the coordinated anions have a subtle effect on the coordination configurations of the Dy³⁺ ions and the magnetic properties of the two Dy₂ complexes. The Dy³⁺ ions in 1 and 2 have the same N₂O₅ coordination environment but show the triangular dodecahedron and the biaugmented trigonal prism coordination configurations, respectively. Magnetic measurements revealed that both 1 and 2 have intramolecular ferromagnetic interactions between the Dy³⁺ ions and show single-molecule magnet behaviors at 0 Oe, with U_eff/k values of 58.2 K for 1 and 59.9 K for 2. These magnetic properties may be explained by theoretical calculations.