1-D hydrogen-bonded organization of hexanuclear {3d-4f-5d} complexes: evidence for slow relaxation of the magnetization for [{LMe2Ni(H2O)Ln(H2O)4.5}2{W(CN)8}2] with Ln = Tb and Dy

Abstract

Heterometallic {3d-4f-5d} aggregates with formula [{L^Me2Ni(H₂O)Ln(H₂O)_4.5}₂{W(CN)₈}₂]·15H₂O, (L^Me2 stands for N,N′-2,2-dimethylpropylenedi(3-methoxysalicylideneiminato) Schiff-base ligand) with Ln = Gd, Tb, Dy, have been obtained by reacting bimetallic [L^Me2Ni(H₂O)₂Ln(NO₃)₃] and Cs₃{W(CN)₈} in H₂O. The hexanuclear complexes are organized in 1-D arrays by means of hydrogen bonds established between the solvent molecules coordinated to Ln and the CN ligands of an octacyanometallate moiety. The X-ray structure was solved for the Tb derivative. Magnetic behavior indicates ferromagnetic {W–Ni} and {Ni–Ln} interactions (J_NiW = 18.5 cm⁻¹, J_NiGd = 1.85 cm⁻¹) as well as ferromagnetic intermolecular interactions mediated by the H-bonds. Dynamic magnetic susceptibility studies reveal slow magnetic relaxation processes for the Tb and Dy derivatives, suggesting SMM type behavior for these compounds.