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

Abstract

The σ-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···O=PX3···(NCF)n (X = F, Cl, Br, H, CH3·; n = 0, 1, 2) complexes were constructed and studied based on the second-order Møller-Plesset perturbation theory (MP2) calculations to investigate the enhancing effects of group V σ-hole interactions on the F···O halogen bond. With increasing n, the FO halogen bond becomes stronger, indicating that the group V σ-hole interactions could enhance the F···O halogen bond. As the capacity of donating electrons of X increases, the most negative electrostatic potentials outside the oxygen atom of O=PX3···(NCF)n (n = 0, 1, 2) become more negative, resulting in a stronger F···O halogen bond. In the formation of a F···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 σ-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.

The competition of Y⋯o and X⋯n halogen bonds to enhance the group V σ-hole interaction in the NCY⋯oPH3⋯NCX and OPH3⋯NCX⋯NCY (X, YF, Cl, and Br) complexes

“…Daudel and Roux put forward the idea of density difference functions more than 50 years ago, which was later applied to studies of the formation of the molecules and weak interaction systems , . For a super molecule A⋯B model, the MFDD can be described as follows: …”

“…The σ‐hole concept was introduced by Murray et al in 2007 for Group V and Group VI covalently bonded atoms, and it was introduced by Murray et al in 2009 for Group IV covalently bonded atoms . From then on, the σ‐hole concept is increasingly being invoked to interpret noncovalent interactions of Group IV–VI atoms …”

Looking Back, Looking Forward at Halogen Bonding in Drug Discovery

“…One such novel bonding chemistry, viz. halogen bonding, has not only permitted ligand-receptor interactions to be further refined and optimized, but also enabled directed design efforts via precise selection of atoms to be incorporated in to the bio-active ligand moieties [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 ]. Halogen bonding is commonly termed as X-bonding given its parallels with H-bonding [ 3 ].…”

A comprehensive analysis of P···π pnicogen bonds: substitution effects and comparison with Br···π halogen bonds

“…One can achieve a more thorough overview by examining the results of density difference of molecular formation (MFDD) analysis [53,[57][58][59]. A detailed picture can be obtained by plotting the difference between the electron density of the complex and the sum of the electron density of free monomers, placed at the same positions that they occupy in the complex.…”