Phase transition in triiodide salts of binuclear ferrocene derivatives having long alkyl chains accompanied by a change in mixed-valence state

Abstract

The relation between the mixed-valence state and crystal structure of 1′,1‴-didecyl- and 1′,1‴-bis(undecyl)-1,1″-biferrocenium triiodide has been studied by means of ⁵⁷Fe Mössbauer spectroscopy and X-ray powder diffraction. The salts with even numbers of carbon atoms in the alkyl chain show a phase transition between two types of layered structures, accompanied by a change in mixed-valence state. Iodine-129 Mössbauer spectroscopy was applied to determine the electronic state of the triiodide anion in the biferrocenium salts. A change in the electronic state accompanied by a phase transition was observed in the case of the 1′,1‴-didecyl derivative.