Intramolecular O–H···O═C Hydrogen Bond Energy via the Molecular Tailoring Approach to RAHB Structures

Abstract

A method for the calculation of the intramolecular hydrogen bond (HB) energy (EHB) by molecular tailoring approach for hydroxycarbonyl aliphatic compounds has been used for compounds with resonance-assisted hydrogen bonding (RAHB). The intramolecular hydrogen bond energies estimated for 229 structures (of 186 compounds) range from 8.2 to 26.3 kcal/mol and show correlation with the geometry descriptors of hydrogen bonds, with the calculated frequencies as well as with topological parameters obtained from the atoms in molecules (AIM) theory. These correlations differ significantly from obtained formerly for saturated nonenolizable structures and prove the special character of the resonance-assisted hydrogen-bonded systems.

Intramolecular hydrogen bond directed stable conformations of benzoyl phenyl oxalamides: unambiguous evidence from extensive NMR studies and DFT-based computations

“…The energies of the HBs (E HB ) for all of the studied molecules were calculated using an empirical relationship E HB ¼Dd + (0.4 AE 0.2) (kcal mol À1 ), [63][64][65] where Dd is the difference in the chemical shis of the hydrogen bonded and free proton. Dd in the present work was derived by subtracting the resonance frequency of the NH proton of molecule 1 from the NH resonance frequencies of the molecules, 2-6, and the E HB values, calculated using the above relationship, are compiled in Table 3.…”

Accurate ab initio calculations of O–H⋯O and O–H⋯−O proton chemical shifts: towards elucidation of the nature of the hydrogen bond and prediction of hydrogen bond distances

“…[89][90][91][92][93][94] According to Gilli et al 89,90 the strength of the hydrogen bond is related to the π electron delocalization due to the mesomeric effect within the conjugated OvC−-CvC−O−H β-diketone enol group. [89][90][91][92][93][94] According to Gilli et al 89,90 the strength of the hydrogen bond is related to the π electron delocalization due to the mesomeric effect within the conjugated OvC−-CvC−O−H β-diketone enol group.…”

Quantitative decomposition of resonance‐assisted hydrogen bond energy in β‐diketones into resonance and hydrogen bonding (π‐ and σ‐) components using molecular tailoring and function‐based approaches

“…This issue is even more complicated in the case of intramolecular RAHB, because the quantitative estimation of the energy of the conventional IMHB is an intractable problem. Nevertheless, Rusinska‐Roszak quantitatively estimated the energy of the O─H⋯O═C IMHB within both a very large series of hydroxycarbonyl aliphatic compounds and the same IMHB in the similar unsaturated structures having the RAHB interaction (mainly β‐diketones) via molecular tailoring approach (MTA). This allows one to quantitatively compare the energy of the RAHB interactions in the unsaturated compounds with that of the non‐RAHBs in the saturated compounds.…”