Application of Linear Free Energy Relationships to Calculated Stabilization Energies of Strained and Unsaturated Molecules

Document Type

Article

Publication Date

1-1-1985

Abstract

Ab initio molecular orbital calculations with the 4-31G basis set have been performed on substituted ethylenes, cyclopropanes, benzenes, and acetylenes. Isodesmic stabilization energies have been compared with corresponding experimental data based upon ΔHf°(g) and very good agreement is observed. Additionally, the calculated stabilization energies have been correlated with substituent constants with both the Taft dual substituent parameter (DSP) equation and Topsom's triple substituent parameter approach. Comparisons of the sensitivities of the four molecular systems to α- and π-substituent effects are made in light of the ionization potentials and electron affinities of the parent hydrocarbons. Substituted ethylenes and benzenes are more sensitive to resonance stabilization by substituents. In contrast, substituted acetylenes are more sensitive to effects associated with the σ-bonding electrons. Cyclopropanes are very weak π-acceptors, but their π-donor abilities are calculated to be greater than vinyl compounds by the stabilization energy criterion. There is a strong correlation between the adiabatic ionization potentials of the four parent hydrocarbons and mR (i.e., ρR) for the four corresponding series of substituted molecules (π-acceptor substituents). © 1985, American Chemical Society. All rights reserved.

Identifier

0001294556 (Scopus)

Publication Title

Journal of the American Chemical Society

External Full Text Location

https://doi.org/10.1021/ja00298a015

e-ISSN

15205126

ISSN

00027863

First Page

3488

Last Page

3494

Issue

12

Volume

107

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