Metal atom dynamics in organometallics: Cyano ferrocenes

Six structurally related cyano ferrocenes have been examined by temperature-dependent Mössbauer effect spectroscopy (MES) to yield information concerning the isomeric shift (IS), quadrupole splitting (QS), and related parameters characterizing the iron atom in these compounds. The IS is related to the s-electron density at the Fe nucleus, while the QS is related to the symmetry and magnitude of the electrostatic field. In addition, these data can yield information related to the dynamics of the metal atom and are in excellent agreement with X-ray crystal data. Density functional theory (DFT) calculations have been used to obtain values for the three principal components of the electric field gradient tensor as well as the electron density at the metal atom site. The results of the DFT calculations and the MES data are found to be in exceptionally good agreement in these compounds.