Mixed-Valence Behavior in an Iodine Complex of a Ferrocenylenesilylene Polymer

Abstract

Structural and thermal characteristics of an amorphous iodine complex of a ferrocenylenesilylene polymer, [−(C5H4)Fe(C5H4)Si(CH3)(C6H5)·(I1.5)−]n, have been measured using 57Fe Mössbauer, IR and Raman spectroscopy, X-ray diffraction, and thermomechanical analysis. The iodine-doped macromolecules are mixed-valence salts with a localized electron structure on the 57Fe Mössbauer time scale, in which ferrocenylene units and ferrocenium moieties coexist. These macromolecules consist of blocks containing ferrocenium moieties and sequences of nonoxidized ferrocenylene units. The environment about the ferrocenium moieties consists of both single I3- and polyiodide [I3]-·nI2 species. Mössbauer data, collected in the range 5−300 K, are interpreted in terms of the temperature dependence of the Lamb−Mössbauer factor and reversible electron transfer with an activation energy of 4.7 kJ/mol. The transformations of [I3]- + I2 clusters to I3- are proposed to accompany Fe(II)−Fe(III) oxidation.