Mononuclear and Trinuclear DyIII SMMs with Schiff-base Ligands Modified by Nitro- Group: First Triangular Complex with N-N Pathway
Using two Schiff-Base ligands containing electron-withdrawing group (NO2), we obtained two mononuclear and two trinuclear complexes of general formula [Dy(hni)(NO3)(DMF)2]∙DMF(1∙DMF), [Dy(hni)2(H2O)2]∙NO3∙EtOH(2∙NO3∙EtOH), and [Dy3(hnc)3(DMF)6](3) and [Gd3(hnc)3(DMF)6] (4) (H-hni: 2-(hydroxyl-3-methoxy-5-nitrophenyl)methylene(isonictino)hydrazine and H3-hnc: 1,5-Bis(2-hydroxy-3-methoxy-5-nitrobenzylidene)carbonohydrazide). Four complexes were confirmed by infrared spectroscopy and single-crystal X-ray diffraction. The crystal structure of complex 3 reveals that the modified Schiff-Base ligand provides two different tridentate coordination pocket (ONN and ONO) to encapsulate DyIII with a unique N-N pathway. Magnetic properties of all four complexes have been investigated using dc and ac susceptibility measurements. The frequency-dependent ac susceptibility is indicative of single-molecule magnet behavior without and/or with optimum dc field with relaxation barrier Ueff = 34 K (400 Oe), 19 K (0 Oe) and 80 K (0 Oe) and for complexes 1, 2 and 3, respectively.