Phenoxido and alkoxido-bridged dinuclear dysprosium complexes showing single-molecule magnet behaviour

Abstract

Two new dysprosium(III) complexes, [Dy₂(HL¹)₄(CO₃)]·4H₂O (1) and [Dy₂(L²)₂(NO₃)₂(CH₃OH)₂]·4CH₃CN (2), have been synthesized from the Schiff-base ligands N′-((2-hydroxy-1-naphthyl)methylene)benzohydrazide (H₂L¹) and N′-((2-hydroxy-1-naphthyl)methylene) picolinohydrazide (H₂L²). Single-crystal X-ray diffraction studies reveal that four mono-deprotonated H₂L¹ ligands and two di-deprotonated H₂L² ligands which have undergone keto–enol tautomerism coordinate to the two dysprosium centres of complexes 1 and 2, respectively. The dc magnetic properties of complexes 1 and 2 are different. The phenoxido bridges in complex 1 mediate antiferromagnetic interaction between Dy^III ions, while ferromagnetic interaction was clearly observed in alkoxido-bridged dinuclear complex 2. Furthermore, both complexes show frequency-dependent ac magnetic susceptibilities, indicating a slow relaxation of the magnetization, typical of SMM behaviour.