Molecular dynamics investigations on mono-, and 1,1′-di-benzoylferrocene from dielectric relaxation measurements in a non-polar solvent

Dielectric relaxation measurements were carried out on mono-, and 1,1′-di-benzoylferrocene in p-xylene in the temperature and frequency range of 293–313 K and 7.5–38.2 GHz, respectively, at various concentrations. For both molecules only one absorption was found in the GHz-region, which can be assigned to whole molecule reorientation and/or (less probably) to the internal rotation around the axis perpendicular to the cyclopentadienyl rings. In both cases a Debye-like behaviour was observed. The following macroscopic dielectric relaxation times (τ) were calculated: compound, T/K, τ/ps; monobenzoylferrocene, 293, 39.8; 303, 37.3; 313, 35.0; dibenzoylferrocene, 293, 63.2; 303, 51.9; 313, 41.2. From the Eyring diagram values of 1.6 and 2.3 kcal.mol⁻¹ were obtained, respectively, for the activation enthalpy of mono-, and di-substituted derivative. A comparison was made among the various ferrocenes studied to date in our laboratory.