Fe57 Mössbauer Effect in Ferrocene Derivatives

The hyperfine structure in the Mössbauer spectrum of Fe57 in ferrocene and in related compounds shows that the bonding of the iron atom is not affected by ring substitution. The temperature dependence of the fraction of recoil-free absorption events in these compounds indicates that the Debye temperature is low (∼150°K) and that the optical modes make only a minor contribution to the reduction of the recoil-free fraction at low temperature.