Heterometallic Octanuclear Ni(II)(4)Ln(III)(4) (Ln = Y, Gd, Tb, Dy, Ho, Er) Complexes Containing Ni(II)(2)Ln(III)(2)O(4) Distorted Cubane Motifs: Synthesis, Structure, and Magnetic Properties

[Image: see text] The reaction of 2-methoxy-6-[{2-(2-hydroxyethylamino)ethylimino}methyl] phenol (LH(3)) with lanthanide metal salts followed by the addition of nickel acetate allowed isolation of a family of octanuclear complexes, [Ni(4)Ln(4)(μ(2)-OH)(2)(μ(3)-OH)(4)(μ-OOCCH(3))(8)(LH(2))(4)]·(OH)(2)·xH(2)O. Single crystal X-ray diffraction studies of these complexes reveal that their central metallic core consists of two tetranuclear [Ni(2)Ln(2)O(4)] cubane subunits fused together by acetate and hydroxide bridges. The magnetic study of these complexes reveals a ferromagnetic interaction between the Ln(III) and the Ni(II) center. The magnitude of exchange coupling between the Ni(II) and Ln(III) center, parametrized from the magnetic data of the Gd analogue, gives J = +0.86 cm(–1). The magneto caloric effect, studied for the Ni(II)(4)Gd(III)(4) complex, shows a maximum of magnetic entropy change, −ΔS(m) = 22.58 J kg(–1) K(–1) at 3 K for an applied external field of 5 T.