Novel Heterometallic Fe−Ru₂−Fe Arrays via “Complex of Complexes” Approach

Four tetranuclear heterometallic compounds, [(Tp)Fe(CN)3]2[Ru2(DMBA)4] (1), [(MeTp)Fe(CN)3]2[Ru2(DMBA)4] (2), [(iBuTp)Fe(CN)3]2[Ru2(DMBA)4] (3), and [(PhTp)Fe(CN)3]2[Ru2(DMBA)4] (4) [DMBA = N,N′-dimethylbenzamidinate, Tp = (hydrotris(pyrazolyl)borate, MeTp = (methyltris(pyrazolyl)borate, iBuTp = (2-methylpropyltris(pyrazolyl)borate, and PhTp = (tris(pyrazolyl)phenylborate)] were prepared from the combination of Ru2(DMBA)4(NO3)2 and an appropriate [(RTp)Fe(CN)3]−. Molecular structures of compounds 1−4 were established using single-crystal X-ray diffraction, and all feature a linear Fe−CN−Ru−Ru−NC−Fe array. The magnetic study revealed that the temperature dependence of χMT is mostly attributed to the zero-field splitting of the Ru2 center, indicating the absence of strong spin coupling among three metallic centers. The electronic independence was further confirmed by the vis−NIR spectroscopic studies. Also described are the voltammetric properties of these compounds.