The ' Variable Electronegativity ' Method. III. The Pyrrole Anion and Electronegativity Reversal

Abstract

The π-electron distribution in the pyrrole anion has been evaluated by the VESCF method using two alternative methods of estimating core attraction terms. The results indicate that the π-electron distribution around the conjugated system is very nearly uniform, supporting previous speculations that the relative attracting powers of tertiary nitrogen and carbon reverse when their π-electron densities exceed a certain value, suspected to be not too much greater than unity. The present calculations indicate that the critical π-electron density is around 1.2. The VESCF estimates of ionization potentials of the pyrrole anion are also reported.