Polarization and apparent dipole moments of some symmetrical molecules

Abstract

Polarization and apparent dipole moments of a series of symmetrical molecules were determined by the standard method in three solvents: benzene, p-xylene, and mesitylene. Their explanation by complex formation with solvent applies only in the case of 1,4-dicyanobenzene and 4,4’-dicyanobiphenyl since the apparent orientation polarizations (PO.app) are large and depend strongly on solvent. On the other hand, 1,4-dihalogenbenzenes do not form any complexes and PO.appis virtually zero. 1,4-Dihalogenbicyclo[2,2,2]octanes reveal also considerable PO.app which is attributed mainly to enhanced atomic polarization but – in the case of heavier halogens – also partly to complexes of unknown structure.