Cl···Cl Interactions in Molecular Crystals: Insights from the Theoretical Charge Density Analysis

Abstract

The structure, IR harmonic frequencies and intensities of normal vibrations of 20 molecular crystals with the X-Cl···Cl-X contacts of different types, where X = C, Cl, and F and the Cl···Cl distance varying from ~3.0 to ~4.0 Å, are computed using the solid-state DFT method. The obtained crystalline wave functions have been further used to define and describe quantitatively the Cl···Cl interactions via the electron-density features at the Cl···Cl bond critical points. We found that the electron-density at the bond critical point is almost independent of the particular type of the contact or hybridization of the ipso carbon atom. The energy of Cl···Cl interactions, E(int), is evaluated from the linking E(int) and local electronic kinetic energy density at the Cl···Cl bond critical points. E(int) varies from 2 to 12 kJ/mol. The applicability of the geometrical criterion for the detection of the Cl···Cl interactions in crystals with two or more intermolecular Cl···Cl contacts for the unique chlorine atom is not straightforward. The detection of these interactions in such crystals may be done by the quantum-topological analysis of the periodic electron density.

Chlorellestadite, Ca5(SiO4)1.5(SO4)1.5Cl, a new ellestadite- group mineral from the Shadil-Khokh volcano, South Ossetia

“…The СlA-ClB distance is 2.81 Å in the studied chlorellestadite (Fig. 4) is shorter than the typical Cl-Cl distance of~3-4Å (Vener et al 2013), which confirms our assumption about mixed Cl + OH(F) occupation of the ClB site.…”

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

“…94 ± 98 Calculations of crystals with this accuracy became possible only recently. 99,100 The results obtained at different levels of the density functional theory were analyzed 101 in order to evaluate the accuracy of reproduction of the geometry and interaction energy in complexes with halogen bonds. Two functionals with correction for dispersion interactions, namely, M06-2X and oB97XD, were recommended.…”

“…Also, linear character of the dependence of the contact energy on the local properties [g(r b ) or n(r b )] may violate if strong hydrogen bonds (7DH > 60 kJ mol 71 ; see Ref. 100) and interactions involving halogen atoms in ion pairs are included in the data set. 230 …”

Influence of Secondary Interactions on the Structure, Sublimation Thermodynamics, and Solubility of Salicylate:4-Hydroxybenzamide Cocrystals. Combined Experimental and Theoretical Study

“…(1). The latter approach provides reasonable values for singlecomponent [37,40] and two-component [24,46] It is assumed that the E latt energy corresponds to the sublimation enthalpy ∆H 0 subl , extrapolated to 0 K. According to [47], the value of the sublimation enthalpy at given temperature T can be written as:…”