[FAAF](-) (A = O, S, Se, Te) or How Electrostatic Interactions Influence the Nature of the Chemical Bond.

The present contribution analyzes the special bonding situation of the [FAAF](-) anions (A = O, S, Se, Te), where the addition on an extra charge turns the covalent A-A bond of the neutral into a charge-shift (CS) bond. By means of theoretical calculations, we demonstrate that electrostatic interactions produced by negative point charges can transform the covalent A-A bond in the A2(+) cation into a CS one. Consequently, the electric field created by the fluorine atoms can be behind the unusual bonding situation of [FAAF](-), showing how electrostatic interactions can influence and alter the nature of the chemical bond.