Dielectric relaxation and molecular dynamics of monoacetylferrocene in a non-polar solvent

A complete molecular dynamic study of monoacetylferrocene has been carried out in p-xylene using dielectric relaxation measurements in the frequency range of 700 MHz-38 GHz at temperatures of 293, 303, 313, and 323 K and at concentrations that vary from 0 to 3% by weight. Under these conditions no intermolecular association or interaction of any type was observed between the solute molecules. As was expected, the compound absorbed in the GHz-region, there being just one very sharp band. At the present stage of our inquiry, this may be assigned to rotation around the molecular axis perpendicular to the two cyclopentadienyl rings or to the molecular reorientation. Treatment of the real and imaginary parts of the complex dielectric permittivity obtained at a concentrarion of 3% (weight fraction) clearly confirmed that the behaviour is very similar to that predicted by the Debye theory. The following macroscopic dielectric relaxation times were calculated: T/K, τ/ps; 293, 26.15; 303, 22.88; 313, 20.66; 323, 18.31. Analysis of these data by means of an Eyring diagram gave the following values for the parameters of the activation of the dielectric relaxation process: ΔH*=1.63±0.3 kcal.mol⁻¹ and ΔS*=−4.86 e.u.