| Abstract: | Solving the constrained Hartree–Fock equation and using the method of the energy component analysis, we have determined the fundamental factor which causes the electrons at the negative center of conjugated carbanion to delocalize over the whole system. Constraint on the π-electron flow between the anion center and polyethylenic system produces the electronic state that the lone-pair electrons are localized at the anionic center. By doing so, a prominent increase in the kinetic energy of π electrons was observed. Such an increase was found to quantitatively fit in with that by the model that electrons are packed in a box. Thus, we could clearly show that delocalization of the carbanion in the polyethylenic system is brought forth by the relaxation of the kinetic energy pressure. We also examined conjugated carbodianion systems. Dianion involves repulsive interaction between anions causing less conjugation energy. Namely, conjugation itself is given by the release in the kinetic energy pressure, but, it is restrained by the electrostatic repulsion. © 1998 John Wiley & Sons, Inc. Int J Quant Chem 68: 65–72, 1998 |
