Dielectric Relaxation and Molecular Structure. VII. Structure of the Molecules of Diphenylene Dioxide Type

The dielectric constants and losses of diphenylene dioxide, phenoxathiin, thianthrene, xanthene and pheno-thiazine have been measured in dilute solution of benzene at the millimeter-wave frequency of 100 GHz at 20 °C. Diphenylene dioxide is found to have a very small dielectric relaxation time which is associated with the change in dipole orientation by the intramolecular change (butterfly motion). The dipole moment of this molecule is small but not considered to be zero. Similar to thianthrene, which has a folded structure about the S–S axis, diphenylene dioxide is also folded about the O–O axis or can easily have a folded structure. Phenoxathiin and the other two molecules have a folded structure and the dielectric relaxation times (at 100 GHz) reveal the effect of the butterfly-flapping motion associated with the barrier height for this internal motion.