Electron transfer rate and structure of [Fe2(bpmp)(ppa)2](BF4)2

Mixed-valence μ-phenolate-bis(μ-carboxylate) diiron(II, III) complex Fe₂(bpmp)(ppa)₂](BF₄)₂ (1) is prepared. The temperature dependence of the M?ssbauer spectra of the complex 1 is measured. The M?ssbauer parameters of the complex 1 show the unusual increase of isomer shift and quadrupole splitting with an increase in temperature. The spectra are explained by the dynamic electronic states in which the valence states of two iron atoms in a molecule are 2.2 and 2.8 on the M?ssbauer time scale at 293 K. The single crystal X-ray structure of the complex 1 is determined at 133 K. The complex 1 crystallizes in the triclinic space group 1. Two iron atoms in the complex 1 are crystallographycally inequivalent.