MIXED-VALENCE STATES OF IRON IN BINUCLEAR FERROCENE COMPOUNDS

Typical experimental results which demonstrate the applicability of Mössbauer spectroscopy to the studies of mixed-valence states of iron atoms are described, especially on biferrocenium and disubstituted biferrocenium salts, which show essentially no appreciable line-broadening at temperatures where the valence-state changes from a trapped to an averaged valence state. The Mössbauer spectroscopic data are compared with some of the results of X-ray crystal structure measurements. An order-disorder transition in valence-state is suggested as one of the plausible explanations for the temperature dependence of the Mössbauer spectrum. Suggestive results of the studies on oxo-centered trinuclear iron carboxylate complexes are also briefly mentioned. © 1990 J.C. Baltzer AG, Scientific Publishing Company.