Dielectric relaxation in clathrates

Abstract

Dielectric parameters (permittivity and loss factors) have been measured for clathrates based on ice (gas hydrates), quinol and Dianin's compound with particular attention to the frequency and temperature ranges displaying the reorientational dipole dispersion of the guest molecules. Many such processes conformed to the simple Debye form. Enthalpies (in kcal mole^–1) and entropies (in cal mole^–1 deg.^–1) of activation for this reorientation were evaluated from Eyring's rate equation, and effective dipole moments (in D) for the guest were derived from the Böttcher-Onsager equation.[graphic omitted]

Most of these ΔH^*_E are less than those for the reorientation of the same or similar molecules in inert solvents.

In Dianin's compound, permittivity data were obtained and the freedom of the dipole to reorient assessed for single molecules of o-C₆H₄Cl₂, C₆H₅NO₂,C₆H₅CN, C₆H₅CH₂CN, t-C₄H₉CN, and for two molecules of HCOOH, CH₃COOH, CH₃NO₂, and (CH₃)₂CO per cavity; for (CH₃CN)₂ per cavity, ΔH^*_E= 2.10±0.15; ΔS^*_E=–2.9; µ= 7.0D; (CH₃CH₂CN)₂ and (CH₃OH)_n gave extended absorptions. The possible resonance form of small-molecule absorptions is considered.