Abstract
The reaction of Ln(NO3)3·6H2O (Ln = Gd, Tb) and Cu(O2CMe)2·H2O with the polydentate Schiff base ligand OHC10H7CHNC(C2H5)(CH2OH)2 (H3L) in Me2CO afforded the heptanuclear heterometallic complexes [Cu5Ln2(O2CMe)2(NO3)4(L)2(HL)2] (Ln = Gd (1), Tb (2)) which were characterized by single-crystal X-ray crystallography (1) and powder XRD measurements (2). Both complexes are isomorphous and consist of a central core {CuII5LnIII2(μ3-OR)6(μ3-O2CMe)2}8+ described as two distorted centrosymmetrically related cubane subunits, {CuII3LnIII(μ3-OR)3(μ3-O2CMe)}5+, with the common apex, Cu(1), residing on an inversion center. Peripheral ligation and bridging is provided by two triply and two doubly deprotonated Schiff base ligands, two μ3-acetates and four chelate nitrates. Magnetic susceptibility measurements revealed the presence of dominant ferromagnetic interactions for both complexes. The magnetocaloric effect of 1 was examined via isothermal magnetization measurements under various applied fields and the maximum entropy change was found equal to 15.7 J kg−1 K−1 at 2 K for ΔH = 5 T. Ac susceptibility measurements of 2 revealed slow magnetic relaxation process suggesting the presence of single-molecule magnet behavior.
Published Version
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