A family of cubane cobalt and nickel clusters: Syntheses, structures and magnetic properties

Five tetranuclear complexes with the composition of [M4(L)4(μ3-OMe)4(MeOH)4], (M = Ni (1) or Co (2), HL is 3,5-dichloro-2-hydroxy-benzaldehyde (Hdchb); M = Ni (3) or Co (4), HL is 2-hydroxy-3-methoxy-benzaldehyde (Hhmb); M = Ni (5), HL is 5-bromo-2-hydroxy-benzaldehyde (Hbhb)), were prepared by reaction of salt perchloride hexahydrate with 2-hydroxy-benzaldehyde ramification under solvothermal conditions. All compounds were characterized by elemental analysis, IR spectroscopy and X-ray single-crystal diffraction. Compounds 1–5 have tetranuclear clusters with a cubane topology in which the metal ions and the oxygen atoms from the methanol ligands occupying the alternate vertices of the cubane. The {M4O4} cores display dominant ferromagnetic interactions from the nature of the binding modes through μ3-OCH3−. No single-molecule magnets (SMMs) behaviors have been observed in complexes 1–3 and 5. In contrast, compound 4 has been observed obviously slow relaxation for the S4 site symmetry and exhibits the behavior of SMMs. The results further support that judicious choice of harmonious mixed ligands provides the means to create a rich variety of new isolated individual {M4O4} cubic system and allows a systematic magnetic study of the effect of intermolecular interactions and correlation.