Abstract
I. In a previous publication This journal 58, 111 (1939). the dipole moments of a number of heterocyclic parent nuclei were measured.II. The most probable structure of these molecules is calculated according to a simple principle of minimum energy described in this publication.III. The object of this publication is to investigate in how far dipole moments of heterocyclic molecules agree to those of the corresponding open‐chain molecules. It was found that the bond moments calculated from cyclic molecules are always greater than those which can be calculated for the corresponding open‐chain molecules. The bond moments calculated from open‐chains molecules are therefore inapplicable for the calculation of the valency angles in heterocyclic molecules from their dipole moments.IV. Description of the results.