Bond angles in nitrogen-containing heterocyclic molecules isoelectronic with benzene

Abstract

It is shown that there is a simple additivity relationship for the bond angles of heterocyclic analogues of benzene with formula [CH] 6-nNn, in which the replacement of CH by N may be treated as if it were a perturbation changing all the angles of the ring by definite amounts. A simple valence-force field which has three effective parameters is constructed so as to reproduce the observed ring angles in these molecules. It appears that the atoms adjacent to a ring nitrogen are significantly affected by the aza-replacement