Modulating Magnetic Anisotropy in Linear Tetranuclear Dysprosium(III) Complexes via Coordinated Anions

We report the synthesis, structures, and magnetic properties of two novel linear tetranuclear complexes with the general formula [Dy₄(Hheb)2(heb)4X₂(MeOH)₄] (X⁻ = NO₃⁻, OAc⁻; H2heb = (E)-N'-(1-(2-hydroxyphenyl)ethylidene)benzohydraz, OAc− = acetate). The rigid ligands (Hheb−/heb2−) incorporates phenoxide groups and bridge the Dy³⁺ ions in an unusual tetranuclear linear assembly. Notably, we demonstrate through magnetic measurements and theoretical calculations how the coordinated anion (X) coordinated at the peripheral Dy³⁺ centers acts as a switch, significantly changing the magnetic anisotropy of the entire complex. This control over magnetic anisotropy through the selection of the coordinated anion offers a promising avenue for tailoring the functionality of Single-Molecule Magnets.