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Multiple Single-Molecule Magnet Behaviors in Dysprosium Dinuclear Complexes Involving a Multiple Functionalized Tetrathiafulvalene-Based Ligand

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journal contribution
posted on 20.04.2015, 00:00 by Min Feng, Fabrice Pointillart, Bertrand Lefeuvre, Vincent Dorcet, Stéphane Golhen, Olivier Cador, Lahcène Ouahab
The reaction between the 2-(1-(2,6-di­(pyrazol-1-yl)-4-methylpyridyl)-4,5-(4,5-bis­(propylthio)-tetrathiafulvalenyl)-1H-benzimidazol-2-yl)-pyridine ligand (L) and 2 equiv of Dy­(hfac)3·2H2O (hfac = 1,1,1,5,5,5-hexafluoroacetylacetonate) and 1 equiv each of Dy­(hfac)3·2H2O and Dy­(tta)3·2H2O (tta = 2-thenoyltrifluoroacetonate) metallic precursors leads to two dinuclear complexes, [Dy2(hfac)6(L)]·(CH2Cl2)2·C6H14 (1) and [Dy2(hfac)3(tta)3(L)] (2), respectively. Their X-ray structures reveal that the two coordination sites are occupied by one DyIII ion. The DyIII ion coordinated to the benzoimidazolylpyridine (bzip) moiety adopts a D4d coordination sphere, while the DyIII ion coordinated to the 2,6-di­(pyrazol-1-yl)-4-pyridine (dpp) moiety is in a D3h surrounding. In a zero dc field, the dynamic magnetic measurements show a slow relaxation for the D4d eight-coordination DyIII magnetization for 1 and 2. Application of an external dc field induces multirelaxation signals of the magnetic susceptibility for both compounds. The low frequency and high frequency of the out-of-phase magnetic signals are attributed to the DyIII ion in D4d and D3h surroundings, respectively. The two complexes can be described as double induced-field mononuclear single-molecule magnets.