Abstract
A family of octanuclear clusters [FeIII4LnIII4O2(OH)4(mosaoH)4 (Piv)4(N-mdea)4(H2O)2] [Ln=Y(1), Gd(2), Tb(3) and Dy(4), mosaoH2=3-Methyloxysalicylaldoxime, N-mdeaH2=N-methyl diethanolamine, pivH=pivalic acid] has been prepared by reactions of [Fe3O(piv)6(OH2)2(OH)]·H2O with Ln(NO3)3·6H2O, mosaoH2 and N-mdeaH2 ligands. The crystal structures of 1–4 were obtained, and their core can be described as two distorted tetrahedral subunits of [Fe2Ln2(μ4–O)] connected by a pair of μ3–OH− groups. A dc magnetic susceptibility study reveals that there exist strong antiferromagnetic interactions between the neibouring Fe atoms. Fitting of the susceptibility data of compound 1 containing diamagnetic YIII ions gives J=−127cm−1. Compound 4 exhibits frequency-dependent out-of-phase ac susceptibility signals indicative of slow magnetization relaxation.
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