Abstract
A mononuclear as well as dinuclear Dy-III complexes of general formula [Dy(hmb)(NO3)(2)(DMF)(2)] (1) and [Dy-2(hmt)(NO3)(4)(DMF)(4)]center dot DMF (2), where Hhmb: (N'-(2-hydroxy-3-methoxybenzylidene)benzohydrazide and H(2)hmt: (N-1,N-4)-N'(1),N'(4)-bis(2-hydroxy-3-methoxybenzylidene)terephthalohydrazide were obtained using a synthetic strategy involving a polytopic Schiff base ligand. Single-crystal X-ray analysis reveals the Dy-III ion is in a distorted pentagonal interpenetrating tetrahedral arrangement. The two symmetrical Dy-III ions in complex 2 exhibit the same geometry and are well-isolated in the molecule by an hmt(2-) ligand. The direct current (dc) and alternating current (ac) magnetic measurements of the compounds were investigated. Complex 1 did not exhibit any ac signal whereas a frequency dependant signal was observed for 2 under zero dc field. When an optimum dc field was applied, clear frequency dependant signals were obtained for both complexes indicative of Single-Ion Magnet behaviour with relaxation barriers of U-eff = 34 and 42 K for 1 and 2, respectively.