Tetranuclear Hetro-Metal [Mn^III₂Ni^II₂] Complexes Involving Defective Double-Cubane Structure: Synthesis, Crystal Structures, and Magnetic Properties

Abstract

Tetranuclear hetero-metal MnIII2NiII2 complexes, [Mn2Ni2(L)4(OAc)2] (1) and [Mn2Ni2(L)4(NO3)2] (2) [H2L = N-(2-hydroxymethylphenyl)-5,6-benzosalicylideneimine], have been synthesized and characterized by X-ray crystal structure analyses, infrared spectra, and elemental analyses. The structure analyses revealed that the complexes have a defective double-cubane metal core connected by μ3-alkoxo bridges. Complexes consist of two bis-μ-alkoxo bridged MnIIINiII heteronuclear units making a dimer-of-dimers structure. The double-cubane cores are significantly distorted due to an effect of syn–syn mode acetato or nitrato bridges. Magnetic measurements indicate that weak antiferromagnetic interactions (Mn-Ni = −0.66 ~ −4.19 cm–1) are dominant in the hetero-metal core.

Keywords

• tetranuclear complex
• hetero-metal complex
• manganese
• nickel
• crystal structure
• double-cubane
• Schiff-base ligand
• magnetic property