Slow Magnetic Relaxation in a Redox-Active Tetrathiafulvalene-Based Ferromagnetic Dysprosium Complex



The association of the two 4,5-bis(thiomethyl)-4′-carboxytetrathiafulvalene (HL1) and 4,5-bis(thiomethyl)-4′-(2-pyridyl-N-oxide)carbamoyltetrathiafulvalene (L2) with the metalloprecursor [Dy(tta)3]·2H2O (tta = 2-thenoyltrifluoroacetonate) leads to the formation of the dinuclear complex of formula [Dy(tta)2(L1)(L2)]2·2CH2Cl2. Static magnetic measurements highlight significant ferromagnetic interactions between the DyIII ions, and dynamic magnetic measurements demonstrate single-molecule-magnet behaviour with an energy barrier of 20 cm–1 and a relaxation time of 8.6(9) × 10–6 s. The thermal dependence of the magnetic susceptibility was evaluated by using a crystal field approach (Stevens operators), which confirmed the Ising character of the system. Finally, electrochemistry shows a complex multiredox system with the successive oxidations of the two tetrathiafulvalene (TTF) ligands.