Cooperative and substitution effects in enhancing the strength of fluorine bonds by anion-π interactions

In this work, the cooperative effects between anion-π and fluorine bond interactions are studied by ab initio calculations at the MP2/6-311++G^** level. Cooperative effects are observed in complexes in which anion-π and fluorine bond interactions coexist. For each complex, the shortening of the binding distance in the fluorine bond is more prominent than that in the anion-π bond. Favorable cooperativity energies are found with values that range between -0.51 and -0.76 kcal/mol. The atoms in molecules and molecular electrostatic potential analyses are carried out for these complexes to understand the nature of anion-π and fluorine bond interactions and the origin of the cooperativity. (author)