A theoretical approach to substituent effects. A comparison of the isoelectronic BH, CH3, and NH groups and their interaction with substituents in disubstituted benzenes
✍ Scribed by Gary Kemister; Addy Pross; Leo Radom; Robert W. Taft
- Publisher
- John Wiley and Sons
- Year
- 1981
- Tongue
- English
- Weight
- 638 KB
- Volume
- 2
- Category
- Article
- ISSN
- 0192-8651
No coin nor oath required. For personal study only.
✦ Synopsis
Abstract
Ab initio molecular orbital theory with the STO‐3G basis set is used to examine both charge and energy interactions in a series of meta‐ and para‐substituted phenylborate anions and toluenes. Comparison of the results is made with data for substituted anilinium cations. It is concluded that whereas NH is a powerful σ acceptor, with essentially no π interaction, BH is primarily a π donor, and, to a slight extent only, a π donor. CH~3~ is indicated to be both a weak σ and π donor. Energies of interaction of BH and NH with a series of substituents are an order of magnitude larger than corresponding values for CH~3~. Interaction energies for BH are of opposite sign to those for NH. The results may be understood qualitatively using perturbation molecular orbital (PMO) theory.