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)benzohydrazide, OAc⁻ = acetate). The rigid ligands (Hheb⁻/heb²⁻) incorporate phenoxide groups and bridge the Dy³⁺ ions in an unusual tetranuclear linear assembly. Notably, we demonstrate through magnetic measurements and theoretical calculations how the 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.