Dielectric Studies. XV. Molecular and Additional Relaxation Process(es) of Some Phenyl-Substituted Compounds

The dielectric constants and losses at wavelengths of 0.860, 1.249, 1.850, and 3.220 cm and the static dielectric constant at 149.9 m have been measured for liquid phenyltrimethylsilane and triphenylsilane, triphenylarsine, triphenylphosphine, and triphenylphosphine oxide in nonpolar solvents at 25°C. Phenyltrimethylsilane and triphenylsilane have significantly shorter relaxation times than a rigid molecule of that size and shape and are to be contrasted with triphenylarsine, triphenylphosphine, and triphenylphosphine oxide. The shortening of the relaxation time seems to become apparent in molecules containing the phenyl group when the molecular dipole moment is low (e.g., ∼0.4 D for the alkylbenzenes).