Syntheses, structures and magnetic properties of a family of heterometallic [MnII2MnIII2LnIII2] clusters

Abstract

A new family of isostructural Mn–Ln heterometallic clusters, [Mn^II₂Mn^III₂Ln^III₂(Piv)₈(thme)₂(H₂tea)₂] (H₃thme = 1,1,1-tris(hydroxymethyl)ethane, Hpiv = pivalic acid, H₃tea = triethanolamine, and Ln = Pr, Nd, Sm, Eu, Gd, Tb, and Dy) have been prepared by reaction of the hexanuclear manganese precursor, [Mn₆O₂(Piv)₁₀(4-Me-Py)_2.5(Hpiv)_1.5], with H₃thme, H₃tea, and Ln(NO₃)₃·6H₂O under the solvothermal conditions. Complexes 1Pr–7Dy were characterized by single-crystal X-ray diffraction and their core [Mn₂^IIIMn₂^IILn₂^III(μ₃-OR)₄(μ₂-OR)₆]⁶⁺ composed of four face-sharing defected cubane units. Antiferromagnetic (AF) exchange interactions were suggested for all of the complexes by solid-state dc magnetic susceptibility measurements. Complexes 6Tb and 7Dy, show frequency-dependent ac susceptibility signals suggestive of slow magnetic relaxation.