Estimations of FH···X hydrogen bond energies from IR intensities: Iogansen's rule revisited

Abstract

In this work the possibility of using the IR intensity of the stretching vibration νs of proton donor group for estimation of hydrogen bond strength was investigated. For a set of complexes with FH···X (X = F, N, O) hydrogen bonds in the wide range of energies (0.1–49.2 kcal/mol) vibrational frequencies νs and their intensities A were calculated (CCSD at complete basis set limit). The validity of the previously proposed linear proportionality between the intensification of the stretching vibration νs in IR spectra and hydrogen bond enthalpy –ΔH = 12.2 ∆A (A. V. Iogansen, Spectrochimica Acta A 1999) was examined. It is shown that for a range of similar hydrogen bond types with complexation energies ∆E <15 kcal/mol the ∆E(∆A) function remains similar to that proposed in the Iogansen's work, while upon strengthening this dependency becomes significantly nonlinear. We examined two other parameters (∆Aνs and ∆A∙mR) related to IR intensity as descriptors of hydrogen bond strength which are proportional to transition dipole moment matrix element and mass‐independent dipole moment derivative. It was found that the dependency ∆E(∆Aνs) stays linear in the whole studied range of complexation energies and it can be used for evaluation of ∆E from infrared spectral data with the accuracy about 2 kcal/mol. The mass‐independent product ∆A∙mR is an appropriate descriptor for sets of complexes with various hydrogen bond types. Simple equations proposed in this work can be used for estimations of hydrogen bond strength in various systems, where experimental thermodynamic methods or direct calculations are difficult or even impossible.

What quantum chemical simulations tell us about the infrared spectra, structure and interionic interactions of a bulk ionic liquid

“…Equation (1) is applicable to 1 : 1 H-bonded complexes, in particular formed by CH moieties, 31 in which the −Δ H HB values are lower than 15 kcal mol −1 . 33 Its applicability to CH⋯[PF 6 ] − 29 and CH⋯[OAc] − 30 HBs in ILs has been demonstrated on a limited number of examples.…”

Evolution of vibrational bands upon gradual protonation/deprotonation of arsinic acid H2As(O)OH in media of different polarity

“…stabilization of polar structures. For neutral complexes (10,33,38,40; regardless, whether they are molecular or zwitterionic) this means an increase of proton transfer coordinate q 1 (data points in Fig. 5a move to the right).…”

“…One can speculate that the electronic shells of proton-donor and proton-acceptor groups in acids with heavier pnictogen atoms, such as, arsinic acids R 1 R 2 As(O)OH, would be even less interacting due to an increase of the metallic properties of the pnictogen. At the moment hydrogen bonding with participation of arsinic acids is poorly studied 36,37 and methods of its spectral diagnostics [38][39][40][41][42][43] are not developed.…”

Complexes of phosphine oxides with substituted phenols: hydrogen bond characterization based on shifts of PO stretching bands

“…Besides, changes in the ν OH band intensity were correlated with the hydrogen bond energy, at least for not very strongly hydrogen-bonded systems. 2,3 There are other correlations too, some of which are outlined in ref. 4.…”