The enhancing effects of group V σ-hole interactions on the F•••O halogen bond

The sigma-hole interaction, which occurs between the covalent IV-VII atoms and nucleophilic substances, has become a hot issue of weak interaction. In this work, NCF center dot center dot center dot O=PX3 center dot center dot center dot(NCF)(n) (X = F, Cl, Br, H, CH3; n = 0, 1, 2) complexes were constructed and studied based on the second-order Moller-Plesset perturbation theory (MP2) calculations to investigate the enhancing effects of group V sigma-hole interactions on the F center dot center dot center dot O halogen bond. With increasing n, the F center dot center dot center dot O halogen bond becomes stronger, indicating that the group V a-hole interactions could enhance the F center dot center dot center dot O halogen bond. As the capacity of donating electrons of X increases, the most negative electrostatic potentials outside the oxygen atom of O=PX3 center dot center dot center dot(NCF)(n) (n = 0, 1, 2) become more negative, resulting in a stronger F center dot center dot center dot O halogen bond. In the formation of a F center dot center dot center dot O halogen bond, along the sequence of X = F, Cl, Br, H, CH3 of the negative sites O=PX3, the electric field of the lone pair of oxygen becomes greater and causes a larger decrease in electron density outside the fluorine atom. On the other hand, with increasing n from 0 to 2, the group V sigma-hole interactions also increase the electric field of lone pair of oxygen and results in a larger decrease in electron density outside the fluorine atom.