Molecular Magnets Based on Homometallic Hexanuclear Lanthanide(III) Complexes

The reaction of lanthanide(III) chloride salts (Gd(III), Dy(III), Tb(III), and Ho(III)) with the hetero donor chelating ligand N'-(2-hydroxy-3-methoxybenzylidene)-6-(hydroxymethyl)picolinohydrazide (LH3) in the presence of triethylamine afforded the hexanuclear Ln(III) complexes [{Ln(6)(L)(2)(LH)(2)}(mu(3)-OH)(4)][MeOH](p)[H2O](q)[Cl](4)center dot xH(2)O center dot yCH(3)OH (1, Ln = Gd(III), p = 4, q = 4, x = 8, y = 2; 2, Ln = Dy(III), p = 2, q = 6, x = 8, y = 4; 3, Ln = Tb(III), p = 2, q = 6, x = 10, y = 4; 4, Ln = Ho(III), p = 2, q = 6, x = 10, y = 2). X-ray diffraction studies revealed that these compounds possess a hexanuclear [Ln(6)(OH)(4)](14+) core consisting of four fused [Ln(3)(OH)](8+) subunits. Both static (dc) and dynamic (ac) magnetic properties of 1-4 have been studied. Single-molecule magnetic behavior has been observed in compound 2 with an effective energy barrier and relaxation time pre-exponential parameters of Delta/k(B) = 46.2 K and tau(0) = 2.85 X 10(-7) s, respectively.