Slow magnetic relaxation in four square-based pyramidal dysprosium hydroxo clusters ligated by chiral amino acid anions – a comparative study

Abstract

The synthesis and characterization of three chiral and one achiral amino acid anion ligated dysprosium hydroxo clusters [Dy₅(OH)₅(α-AA)₄(Ph₂acac)₆] (α-AA = D-PhGly, L-Pro, L-Trp, Ph₂Gly; Ph₂acac = dibenzoylmethanide) are reported. The solid state structures were determined using single crystal X-ray diffraction and show that five Dy(III) ions are arranged in a square-based pyramidal geometry with NO₇-donor-sets for the basal and O₈-donor-sets for the apical Dy atom. Both static (dc) and dynamic (ac) magnetic properties were investigated for all four compounds and show a slow relaxation of magnetization, indicative of single molecule magnet (SMM) behaviour below 10 K in all cases. The similar SMM behaviour observed for all four compounds suggests that the very similar coordination geometries seen for the dysprosium atoms in all members of this family, which are independent of the amino acid ligand used, play a decisive role in steering the contribution of the single ion anisotropies to the observed magnetic relaxation.