A diabolo-shaped Dy9 cluster: synthesis, crystal structure and magnetic properties

Abstract

The reaction of Dy(NO₃)₃·6H₂O with the ligand 2-((1-hydroxybutan-2-ylimino)methyl)phenol (H₂L, Scheme 1) generates the nonanuclear compound [Dy₉L₈(μ₃-OH)₈(μ₄-OH)₂(CH₃OH)₈](OH)(CH₃OH)₃ (Dy₉), whose single-crystal X-ray structure reveals the presence of two square pyramidal pentanuclear units assembled via the apical metal center. The square pyramidal core of a previously reported [Dy₅(μ₄-OH)(μ₃-OH)₄(μ-η²-Ph₂acac)₄(η²-Ph₂acac)₆] (Dy₅; Ph₂acac = dibenzoylmethanide), is structurally related to those herein described; however, the magnetic properties of Dy₉ and Dy₅ are drastically different. Indeed, Dy₅ shows slow relaxation of magnetization while no out-of-phase ac signal is noticed for Dy₉. The underlying mechanism is not clear due to the complexity of such systems; however, the different anisotropy of the respective structures, which is dictated by the combination of the metal topology, the ligands involved and the structural parameters of the molecule, is mostly responsible for the distinctive relaxation dynamics observed.