Bent bonds, the antiperiplanar hypothesis and the theory of resonance. A simple model to understand reactivity in organic chemistry

Abstract

By taking into consideration bent bonds (τ-bonds, tau-bonds), the antiperiplanar hypothesis, the classic theory of resonance, and the preference for staggered bonds over eclipsed bonds in tetrahedral systems, a simple qualitative model is presented to rationalize the conformation and reactivity for a wide range of compounds containing double bonds and/or carbonyl groups. Alkenes, carbonyl and carboxyl derivatives, conjugated systems as well as other functional groups are revisited. This also leads to a simple model to understand aromaticity, and electrocyclic reactions. The bent bond model and the antiperiplanar hypothesis provide a qualitative model for better understanding the electron delocalization and the reactivity inherent to unsaturated organic systems by an alternative view of the classic resonance theory.