Polarization of π-electron systems by substituent dipoles and poles

Abstract

Theoretical calculations, at the ab initio STO-3G, 3-21G, and 4-31G bases, have been used to investigate the polarization of π-electron systems by substituent dipoles and poles. Isolated molecule calculations show a dependence in the third power of the distance for dipoles and the second power for poles and gives an approximate measure of the polarizability of different molecules such as ethylene, acetylene, benzene, and formaldehyde. Polarization of conjugated dienes and trienes leads to charge alteration in accord with simple resonance ideas rather than affecting the π-system as a whole. The π-system in benzenes undergoes polarization partly as a whole and party in accord with resonance concepts.