Metal atom dynamics in organometallics: Vibrational amplitude determination for bis phosphino ferrocenes including a waxy system

Three structurally related bis phosphino ferrocene complexes have been examined by 57Fe Mössbauer effect (ME) spectroscopy in order to evaluate the hyperfine interaction parameters (IS and QS), their temperature dependencies, as well as the dynamics of the metal atom over a temperature range. For two of the compounds (1 and 2), for which single crystal X-ray diffraction data have been reported, a direct comparison can be effected between the Ui,j values derived from the X-ray study and that extracted from the ME data, and are found to be in good agreement. For complex 3, which is a waxy material at room temperature, no X-ray data can be obtained, but the ME data permit an evaluation of the metal atom vibrational amplitudes even in the high (>180 K) temperature regime. In addition, data are presented relating to the anisotropy of the metal atom motion in these ferrocene complexes.