Fast Quantum Approach for Evaluating the Energy of Non-Covalent Interactions in Molecular Crystals: The Case Study of Intermolecular H-Bonds in Crystalline Peroxosolvates

Abstract

Energy/enthalpy of intermolecular hydrogen bonds (H-bonds) in crystals have been calculated in many papers. Most of the theoretical works used non-periodic models. Their applicability for describing intermolecular H-bonds in solids is not obvious since the crystal environment can strongly change H-bond geometry and energy in comparison with non-periodic models. Periodic DFT computations provide a reasonable description of a number of relevant properties of molecular crystals. However, these methods are quite cumbersome and time-consuming compared to non-periodic calculations. Here, we present a fast quantum approach for estimating the energy/enthalpy of intermolecular H-bonds in crystals. It has been tested on a family of crystalline peroxosolvates in which the H∙∙∙O bond set fills evenly (i.e., without significant gaps) the range of H∙∙∙O distances from ~1.5 to ~2.1 Å typical for strong, moderate, and weak H-bonds. Four of these two-component crystals (peroxosolvates of macrocyclic ethers and creatine) were obtained and structurally characterized for the first time. A critical comparison of the approaches for estimating the energy of intermolecular H-bonds in organic crystals is carried out, and various sources of errors are clarified.

Non-covalent interactions of the hydroperoxo group in crystalline adducts of organic hydroperoxides and their potassium salts

“…40,57 Incorporating periodic boundary conditions makes it possible to obtain the spectroscopic, 58 metric 38–40 and electron density 59,60 characteristics needed to evaluate energies/enthalpies of intermolecular H-bonds. 20,57,61…”

“…For example, strong H-bonds may not be implemented in gas phase cluster geometries. 40,57 Incorporating periodic boundary conditions makes it possible to obtain the spectroscopic, 58 metric [38][39][40] and electron density 59,60 characteristics needed to evaluate energies/enthalpies of intermolecular H-bonds. 20,57,61 To the best of our knowledge, the H-bond energies/ enthalpies of HPCA in the solid state have never been estimated before.…”

“…40,57 Incorporating periodic boundary conditions makes it possible to obtain the spectroscopic, 58 metric [38][39][40] and electron density 59,60 characteristics needed to evaluate energies/enthalpies of intermolecular H-bonds. 20,57,61 To the best of our knowledge, the H-bond energies/ enthalpies of HPCA in the solid state have never been estimated before. The quantitative analysis of organic hydroperoxide H-bonds must be carried out considering the nature of the proton acceptor group.…”

“…65 The Espinosa approach gives reasonable results for energies of intermolecular H-bonds and other non-covalent interactions in organic crystals varying from 2.0 to 50 kJ mol −1 . 57 The details of periodic DFT calculations are given in the ESI † (section "Computational method"; Table S5). It was previously shown that B3LYP/6-31G** level well reproduced the metric parameters of H-bonded fragments in crystals with ionic and zwitterionic species.…”

“…The calculated enthalpy values are lower than the energy values in all cases, which is in good agreement with the literature data. 57 This journal is © The Royal Society of Chemistry 2022…”