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), [((i)BuTp)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, (i)BuTp = (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[triple bond]N-Ru-Ru-N[triple bond]C-Fe array. The magnetic study revealed that the temperature dependence of chi(M)T 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.