Synthesis, structure and magnetic properties of a novel family of heterometallic nonanuclear Na~I_2Mn~(III)_6Ln~(III) (Ln = Eu, Gd, Tb, Dy) complexes

摘要

The structures and magnetic properties of four isomorphous nonanuclear heterometallic complexes [Na_2{Mn_3~(III)(μ _3-O~(2-))}_2Ln~(III)(hmmp) _6(O_2CPh)_4(N_3)_2] OH·0.5 CH_3CN·1.5H_2O are reported, where Ln~(III) = Eu (1), Gd (2), Tb (3) and Dy (4), H_2hmmp = 2-[(2-hydroxyethylimino)methyl]-6-methoxyphenol. Complexes 1-4 were prepared by the reactions of hmmpH_2 with a manganese salt and the respective lanthanide salt together with NaO_2CPh and NaN_3. Single-crystal X-ray diffraction analyses reveal that the six Mn~(III) and one Ln~(III) metal topology in the aggregate can be described as a bitetrahedron. The two peripheral [Mn~(III)_3(μ _3-O~(2-))]~(7+) triangles are each bonded to a central Ln~(III) ion with rare distorted octahedral geometry. The magnetic properties of all the complexes were investigated using variable temperature magnetic susceptibility and both antiferromagnetic and ferromagnetic interactions exist in the [Mn~(III)_3(μ_3-O ~(2-))]~(7+) triangle. Weak ferromagnetic exchange between the Ln~(III) and Mn~(III) ions has been established for the corresponding Gd derivative. The Gd, Tb and Dy complexes show no evidence of slow relaxation behaviour above 2.0 K.