Assembling Dysprosium Dimer Units into a Novel Chain Featuring Slow Magnetic Relaxation via Formate Linker.

A dinuclear complex [DyLClCHOH)] (1) and a one-dimensional compound [DyL(HCOO)(CHOH)] (2) have been synthesized using an organic ligand of N'-(2-hydroxybenzylidene)picolinohydrazide (HL). Complex 1 exhibits a symmetric dinuclear structure, in which the Dy centers reside in a pentagonal-bipyramidal coordination environment. In 2, the dinuclear units of 1 are strung into chains by formate anions, in which Dy ions are situated in an octa-coordinated, hula-hoop-like coordination geometry. Magnetic studies reveal that ferromagnetic coupling is found between Dy ions in both compounds. Complexes 1 and 2 exhibit slow magnetic relaxation under zero dc field with effective energy barriers of 88.4 and 175.8 K, respectively. Magnetic study combined with ab initio calculations indicates that the better performance of 2 is related to the unique molecular geometry and relatively stronger Dy-Dy magnetic interaction within and/or between the dimer units.