Recent results obtained at the CEISAM laboratory on the astatine chemistry are highlighted on the front cover of the Physical Chemistry Chemical Physics journal, dated February 21, 2021.

The increase in the mass of electrons with their speed modifies their behavior within the atoms. Astatine being the last element of the halogen family, its chemistry is expected to be the most affected by relativistic effects. However, the ability of the iodine atom to form halogen bonds is more affected by relativistic effects than that of astatine in some molecules. Molecular modeling simulations have shown that the phenomenon is related, on the one hand, to the propagation of polarization over the chemical bonds, and, on the other hand, to the delocalization of electrons over the chemical bonds. These two electronic effects (inductive and mesomeric), usually present in molecules, allow the relativistic effects generated by astatine’s electrons to be transmitted to a vicinal iodine atom.

This result represents a first proof of a transfer of relativistic effects with significant impact on the chemical reactivity, here the ability of a molecule to form intermolecular interactions.

Contact : Nicolas Galland