The syntheses, structural determinations and magnetic studies of tetranuclear MIILnIII complexes (M = Ni, Zn; Ln = Y, Gd, Dy) involving an in situ compartmentalized schiff base ligand HL derived from the condensation of o-vanillin and 2-hydrazinopyridine as main ligand are described. Single-crystal X-ray diffraction reveals that all complexes are closely isostructural, with the central core composed of distorted {M2Ln2O4} cubes of the formulas [Ni2Ln2(μ3-OH)2(L)2(OAc)4(H2O)3.5](ClO4)2·3H2O (Ln = Y 1 and Gd 2), [Ni2Dy2(μ3-OH)2(L)2(OAc)5(EtOH)(H2O)1.5](ClO4)·EtOH·H2O (3) and [Zn2Ln2(μ3-OH)2(L)2(OAc)5(EtOH)(H2O)](ClO4)·2EtOH·1.5H2O (Gd 4 and Dy 5). The LnIII ions are linked by two hydroxo bridges and each MII ion is also involved in a double phenoxo-hydroxo bridge with the two LnIII ions, so that each hydroxo group is triply linked to the two LnIII and one MII ions. The magnetic properties of all complexes have been investigated. Ni2Y2 (1) has a ferromagnetic NiII⋯NiII interaction. A weak ferromagnetic NiII⋯LnIII interaction is observed in the Ni2Ln2 complexes (Ln = Gd 2, Dy 3), along with a weak antiferromagnetic LnIII⋯LnIII interaction, a D zero-field splitting term for the nickel ion and a ferromagnetic NiII⋯NiII interaction. The isomorphous Zn2Ln2 (Ln = Gd 4, Dy 5) does confirm the presence of a weak antiferromagnetic LnIII⋯LnIII interaction. The Ni2Dy2 complex (3) does not behave as a SMM, which could result from a subtractive combination of the Dy and Ni anisotropies and an increased transverse anisotropy, leading to large tunnel splittings and quantum tunneling of magnetization. On the other hand, Zn2Dy2 (5) exhibits a possible SMM behavior, where its slow relaxation of magnetization is probably attributed to the presence of the anisotropic DyIII ions.
You have access to this article
Please wait while we load your content...
Something went wrong. Try again?