Intervalence transfer in a new benzotriazolate bridged ruthenium-iron complex

The unsymmetrical dinuclear ruthenium-iron complexes [(NH3)(5)Ru-bta-Fe(CN) (5)](n) (where bta = benzotriazolate; n = -2, -1, 0) were prepared as solid sodium salts from [Ru-II(NH3)(5)(bta)](+) or [Ru-III(NH3)(5)(bta)](2+) and [Fe-II(CN)(5)(H2O)](3-) and characterized in aqueous solution by means of electrochemical and spectroelectrochemical methods. UV-vis, near-infrared, IR, and cyclic and differential pulse voltammetry data suggest that the rel ated mixed valent species belong to a valence trapped formulation, featurin g localized Ru(III) and Fe(II) oxidation states. In spite of the class II c ategorization in the Robin and Day scheme, this system shows a remarkable m etal-metal electronic coupling, as deduced from an intense, low-energy, and very broad intervalence band in the near-IR region. In addition, the mixed valence state displays enhanced stabilization in relation to the isovalent state. The intervalence transfer properties are discussed on the basis of Hush's theory.