The reaction of DyBr3 with the Schiff base ligand N-salicylidene-o-aminophenol (saphH2) in the presence of NEt3 under a MeOH/MeCN solvent mixture has afforded the new nonanuclear cluster [Dy9(OH)8(saph)8(MeCN)(MeOH)5(H2O)3]Br3 (1) in good yield. Single-crystal X-ray diffraction studies revealed that 1 comprises a structurally unprecedented {Dy9(μ3-OH)8(μ3-OR)2(μ-OR)10}7+ core assembled through the combined bridging action of eight μ3-OH− ions and the phenoxido groups of eight fully deprotonated saph2− ligands adopting three distinct coordination modes. The metallic skeleton can be described as a central windmill-like {Dy7} unit decorated by two additional DyIII ions or, alternatively, as eight edge-sharing {Dy3(μ3-OH)}8+ triangular subunits. To the best of our knowledge, such a topology has no structural precedence in homometallic 4f-metal cluster chemistry. Direct-current magnetic susceptibility measurements indicate the presence of weak antiferromagnetic interactions and magnetic anisotropy arising from the DyIII ions. Alternating-current magnetic studies reveal frequency-dependent out-of-phase signals under zero applied dc field, indicating slow relaxation of the magnetization, although efficient quantum tunnelling processes prevent the observation of well-defined maxima. The present results further demonstrate the remarkable ability of the saph2− Schiff base ligand to facilitate the self-assembly of high-nuclearity dysprosium clusters with unusual topologies and interesting magnetic properties.
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