Syntheses, structures, and magnetic analyses of a family of heterometallic hexanuclear [Ni _4M _2] (M = Gd, Dy, Y)compounds: Observation of slow magnetic relaxation in the dyiii derivative

摘要

We described the syntheses, crystal structures, and magnetic behavior of a novel series of heterometallic [Ni _4M _2] [M = Gd (1), Dy (2)and Y (3)] hexanuclear compounds afforded by the reaction of rare-earth(III)nitrate, nickel(II)acetate, and Schiff-base ligand 2-(2-hydroxy-3-methoxybenzylideneamino)phenol (H _2L)in a mixture of ethanol and dichloromethane in the presence of triethylamine. Single-crystal X-ray diffraction measurements reveal that all three compounds have a metal core made up of two Ni _2MO _4 defective cubanes. The magnetic properties of all compounds have been studied. Solid-state direct-current magnetic susceptibility analyses demonstrate competing antiferromagnetic and ferromagnetic interactions within both compounds 1 and 3. Solid-state alternating-current magnetic susceptibility investigations show a frequency-dependent out-ofphase signal for compound 2 below 4 K, suggestive of slow magnetic relaxation.