Polarisation of Electron Density and Electronic Effects: Revisiting the Carbon-Halogen Bonds.

Electronic effects (inductive and mesomeric) are of fundamental importance to understand the reactivity and selectivity of a molecule. In this article, polarisation temperature is used as a principal index to describe how electronic effects propagate in halogeno-alkanes and halogeno-alkenes. It is found that as chain length increases, polarisation temperature decreases. As expected, polarisation is much larger for alkenes than for alkanes. Finally, the polarisation mode of the carbon-fluorine bond is found to be quite different and might explain the unusual reactivity of fluoride compounds.