An ionic dysprosium complex made of a hexanuclear Dy6 cationic cluster and a mononuclear Dy anionic unit
Résumé
A genuine 2-hydroxy-N′-[3-(hydroxyimino)butan-2-ylidene]benzohydrazide ligand, characterized by 1H, 13C, and 15N NMR spectroscopy and chemical analysis, has been used to synthesize a novel ionic dysprosium species. The structural determination confirms the existence of a hexanuclear Dy cationic entity along with a mononuclear Dy anionic unit. The topological analysis of the hexanuclear cluster indicates that it corresponds to a 2,4M6–1 graph, observed for the first time for Dy complexes. The electrostatic model for the determination of the magnetic anisotropy in Dy complexes implemented in the Magellan program confirms that it is difficult to control the orientation of the different anisotropy axes of the six Dy ions in order to obtain large anisotropy in polynuclear Dy entities, which is in agreement with the ac susceptibility measurements that show frequency-dependent signals and absence of maxima for the out-of-phase susceptibility signals above 2 K, even under a dc bias field of 0.1 T or 0.2 T.