A Molecular Electrostatic Potential Analysis of Hydrogen, Halogen, and Dihydrogen Bonds

Abstract

Hydrogen, halogen, and dihydrogen bonds in weak, medium and strong regimes (<1 to ∼ 60 kcal/mol) have been investigated for several intermolecular donor-acceptor (D-A) complexes at ab initio MP4//MP2 method coupled with atoms-in-molecules and molecular electrostatic potential (MESP) approaches. Electron density ρ at bond critical point correlates well with interaction energy (Enb) for each homogeneous sample of complexes, but its applicability to the entire set of complexes is not satisfactory. Analysis of MESP minimum (V(min)) and MESP at the nuclei (Vn) shows that in all D-A complexes, MESP of A becomes more negative and that of D becomes less negative suggesting donation of electrons from D to A leading to electron donor-acceptor (eDA) interaction between A and D. MESP based parameter ΔΔVn measures donor-acceptor strength of the eDA interactions as it shows a good linear correlation with Enb for all D-A complexes (R(2) = 0.976) except the strongly bound bridged structures. The bridged structures are classified as donor-acceptor-donor complexes. MESP provides a clear evidence for hydrogen, halogen, and dihydrogen bond formation and defines them as eDA interactions in which hydrogen acts as electron acceptor in hydrogen and dihydrogen bonds while halogen acts as electron acceptor in halogen bonds.

Interplay between non-covalent interactions in complexes and crystals with halogen bonds

“…77 It was found that in most molecules the potential around the fluorine atoms characterized by the highest electronegativity remains negative. 78,79 For chlorine, bromine and iodine atoms, a region of positive potential values is formed along the extension of the C7X covalent bond line.…”

Intermolecular carbon–carbon, nitrogen–nitrogen and oxygen–oxygen non-covalent bonding in dipolar molecules

“…(a)). Recently, Mohan and Suresh 54 showed that a correlation between ρ and interaction energy is 50 applicable only for homogenous groups of complexes. The E int is also found to increases with increase in the dipole moment μ of the molecule (Figure 3.…”

“…MO analysis was done to 25 confirm the bonding interactions corresponding to the intermolecular bond critical points shown by the AIM analysis. Molecular electrostatic potential (MESP), defined by equation (1) can be used as a tool for understanding intermolecular interactions [51][52][53][54] . It directly reflects the charge distribution in the 30 system, based upon Coulomb's law 55 .…”

Theoretical vs. Experimental Ir Frequency Shifts Upon Π- Hydrogen Bonding: Complexes of Substituted Phenols With Hexamethylbenzene

“…In a number of studies from our laboratory, we have established that EPN is a remarkably accurate descriptor of the abilities of specific atomic centers in molecules to form hydrogen bonds [42][43][44][45][46][47] and also in quantifying chemical reactivity [48][49][50][51]. In later years, EPN values have been successfully employed by other authors in examining reactivity trends [52][53][54][55][56][57][58][59][60]. Politzer and Thruhlar [61] defined the electrostatic potential at nuclei Y (V Y ) by Eqn.…”