Tetranuclear Hetro-Metal [Mn2IIINip2II] Complexes Involving Defective Double-Cubane Structure: Synthesis, Crystal Structures, and Magnetic Properties

Tetranuclear hetero-metal Mn(2)(III)Nip(2)(II) 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 mu(3)-alkoxo bridges. Complexes consist of two bis-mu-alkoxo bridged (MnNiII)-Ni-III 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 similar to -4.19 cm(-1)) are dominant in the hetero-metal core.