Rational Design of a Lanthanide-Based Complex Featuring Different Single-Molecule Magnets

International audienceThe rational synthesis of the 2-\1-methylpyridine-N-oxide-4,5-[4,5-bis(propylthio)tetrathiafulvalenyl]-1H-benzimidazol-2-yl\pyridine ligand (L) is described. It led to the tetranuclear complex [Dy4 (tta)12 (L)2 ] (Dy-Dy2 -Dy) after coordination reaction with the precursor Dy(tta)3 ⋅2 H2 O (tta(-) =2-thenoyltrifluoroacetonate). The X-ray structure of Dy-Dy2 -Dy can be described as two terminal mononuclear units bridged by a central antiferromagnetically coupled dinuclear complex. The terminal N2 O6 and central O8 environments are described as distorted square antiprisms. The ac magnetism measurements revealed a strong out-of-phase signal of the magnetic susceptibility with two distinct sets of data. The high- and low-frequency components were attributed to the two terminal mononuclear single-molecule magnets (SMMs) and the central dinuclear SMM, respectively. A magnetic hysteresis loop was detected at very low temperature. From both structural and magnetic points of view, the tetranuclear SMM Dy-Dy2 -Dy is a self-assembly of two known mononuclear SMMs bridged by a known dinuclear SM