Intermolecular hydrogen bond energies in crystals evaluated using electron density properties: DFT computations with periodic boundary conditions

Abstract

The hydrogen bond (H-bond) energies are evaluated for 18 molecular crystals with 28 moderate and strong O-H···O bonds using the approaches based on the electron density properties, which are derived from the B3LYP/6-311G** calculations with periodic boundary conditions. The approaches considered explore linear relationships between the local electronic kinetic G(b) and potential V(b) densities at the H···O bond critical point and the H-bond energy E(HB). Comparison of the computed E(HB) values with the experimental data and enthalpies evaluated using the empirical correlation of spectral and thermodynamic parameters (Iogansen, Spectrochim. Acta Part A 1999, 55, 1585) enables to estimate the accuracy and applicability limits of the approaches used. The V(b)-E(HB) approach overestimates the energy of moderate H-bonds (E(HB) < 60 kJ/mol) by ~20% and gives unreliably high energies for crystals with strong H-bonds. On the other hand, the G(b)-E(HB) approach affords reliable results for the crystals under consideration. The linear relationship between G(b) and E(HB) is basis set superposition error (BSSE) free and allows to estimate the H-bond energy without computing it by means of the supramolecular approach. Therefore, for the evaluation of H-bond energies in molecular crystals, the G(b) value can be recommended to be obtained from both density functional theory (DFT) computations with periodic boundary conditions and precise X-ray diffraction experiments.

Conformations, vibrational spectra and force field of 1-methyl-2-(2′-pyridyl)benzimidazole: experimental data and density functional theory investigation in comparison with 2-(2′-pyridyl)benzimidazole

“…This region in the IR spectrum of 2PBI is very similar to the IR spectrum of the hydrogen bonded imidazole crystal (so-called imidazole N-H effect) when the presence of this complicated band is explained by the statistical disorder in crystalline lattice, due to bending of the H-bonds [50][51][52]. Similar strong coupling effects have also been observed in IR spectra of crystals with strong O-H…O bonds for some other compounds [53,54]. A pair of intensive bands near 1467 and 1443 cm -1 in IR spectrum of 2PBI have the counterparts in IR spectrum of Me2PBI at 1471 and 1447 cm -1 both assigned to the CH in-plane bending of Py fragment.…”

Diiodomethane as a halogen bond donor toward metal-bound halides

“…Vener et al 64 (Tables 2 and S1 †) and one can state that the strength of these non-covalent interactions (2.2-2.8 kcal mol −1 ) is comparable with those of weak hydrogen bonds following the classification of Jeffrey ("strong": 40-15 kcal mol −1 , "moderate": 15-4 kcal mol −1 , "weak": <4 kcal mol −1 ). 67 The balance between the Lagrangian kinetic energy G(r) and potential energy density VIJr) at the BCPs (3, −1) reveals the nature of these interactions.…”

Understanding of Noncovalent Interactions Involving Organic Fluorine

“…In the work, a molecular pair consisting of C-H···F interactions were extracted from the crystal packing and analyzed by the PIXEL method [102,103] and Atoms in Molecule (AIM) [105,106] theory. From the PIXEL energy calculations, it was obtained that the interaction energy of a molecular pair containing short C-H···F-C [107] (ii) D.E G (int) = 0.429 G b (in atomic units) [108,109]; where D.E(int) is the dissociation energy of the interaction. Interaction energy (I.E) = −D.E V b and G b are local potential and kinetic energy density at the bond critical points (BCP) respectively.…”