Synthesis, structure and magnetic properties of cyclic 3d metal clusters based on N–N single bonds of diacylhydrazine ligand

Abstract

Two cyclic high-nuclearity 3d metal clusters formulated as [CoII8CoIII4(bdsh)4(Py)12(MeOH)4(OAc)4]·14CH3OH·4H2O ({Co12} cluster) and [MnII4MnIII12MnIV4(bdsh)10(Py)2(DMF)8(H2O)8]·16DMF·2CH3OH·8H2O ({Mn20} cluster), (H6bdsh = N,N'-bis(2-salicylhydrazide)isophthalohydrazide, Py = pyridine, and DMF = N,N'-dimethylformamide), were synthesized by a conventional solution method. The {Co12} cluster presents a dodecanuclear ring structure consisting of two symmetrical hemicyclic skeletons bridged with two cobalt ions through the phenolic hydroxyl oxygen atom of H6bdsh ligand, the hemicyclic skeleton in which five cobalt ions are bridged by four N–N single bonds of diacylhydrazine ligands. The {Mn20} cluster exhibits a double cyclic structure comprising of two decanuclear ring skeleton bridged with two phenolic hydroxyl oxygen atoms of H6bdsh ligands, the decanuclear skeleton in which ten manganese ions are bridged by ten N–N single bonds of five H6bdsh ligands. Magnetic studies reveal the existence of antiferromagnetic interactions in both {Co12} and {Mn20} clusters.