The nature of the inductive effect of azinyl groups
The induction constants of azinyl groups are factored into two components, a σ-induction (σX) and a field (σF) component. It is shown that the σX constants of azinyl groups can be thought of as sums of contributions from the phenyl group and the endocyclic nitrogen atoms. A satisfactory correlation is found between the σF constants and the size and direction of the dipole moment of the heterocyclic substituents in the framework of the Kirkwood-Westheimer equation.