ChemInform Abstract: Application of 14N and 15N NMR for Determination of Protonation Site and Hydrogen Bond Strength in Nitrogen Organic Compounds

ChemInform ◽  
2010 ◽  
Vol 32 (22) ◽  
pp. no-no
Author(s):  
Wojciech Schilf ◽  
Lech Stefaniak
Keyword(s):  
Hydrogen Bond ◽  
Bond Strength ◽  
Organic Compounds ◽  
15N Nmr ◽  
Protonation Site ◽  
Hydrogen Bond Strength

Bonding topology, hydrogen bond strength, and vibrational chemical shifts on hetero-ring hydrogen-bonded complexes — Theoretical insights revisited

2012 ◽  
Vol 90 (4) ◽  
pp. 368-375 ◽  
Author(s):  
Boaz G. Oliveira ◽  
Regiane C. M. U. Araújo
Keyword(s):  
Hydrogen Bond ◽  
Bond Strength ◽  
Chemical Shifts ◽  
Dipole Moments ◽  
Interaction Strength ◽  
Hydrogen Bond Strength ◽  
Electronic Densities ◽  
Bonded Complexes ◽  
Hydrogen Bonded

This work presents a theoretical study about the interaction strength of the hydrogen-bonded complexes C2H4O···HF, C3H6O···HF, C2H4O···HCF3, and C3H6O···HCF3 at the B3LYP/6–311++G(d,p) level. The structures, hydrogen bond energies, charge transfers, and dipole moments of these complexes were analyzed in accordance with routine spectroscopy events, such as the red- and blue-shifts on the stretch frequencies of the proton donors (HF and HCF3). The ChelpG atomic charges were used to quantify the charge-transfer fluxes from electron donor (O) towards to acceptors (HF or HCF3). Moreover, the topological calculations on the basis of the quantum theory of atoms in molecules (QTAIM) approach were also used to unveil the hydrogen bond strength (O···H), mainly in the determination of their electronic densities and Laplacian shapes.

Redshift or Adduct Stabilization—A Computational Study of Hydrogen Bonding in Adducts of Protonated Carboxylic Acids

2009 ◽  
Vol 15 (2) ◽  
pp. 239-248 ◽  
Author(s):  
Solveig Gaarn Olesen ◽  
Steen Hammerum
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonds ◽  
Bond Strength ◽  
Bond Length ◽  
Carboxylic Acids ◽  
Computational Study ◽  
Proton Affinities ◽  
Oh Groups ◽  
Hydrogen Bond Strength ◽  
Length Changes

It is generally expected that the hydrogen bond strength in a D–H•••A adduct is predicted by the difference between the proton affinities (Δ PA) of D and A, measured by the adduct stabilization, and demonstrated by the infrared (IR) redshift of the D–H bond stretching vibrational frequency. These criteria do not always yield consistent predictions, as illustrated by the hydrogen bonds formed by the E and Z OH groups of protonated carboxylic acids. The Δ PA and the stabilization of a series of hydrogen bonded adducts indicate that the E OH group forms the stronger hydrogen bonds, whereas the bond length changes and the redshift favor the Z OH group, matching the results of NBO and AIM calculations. This reflects that the thermochemistry of adduct formation is not a good measure of the hydrogen bond strength in charged adducts, and that the ionic interactions in the E and Z adducts of protonated carboxylic acids are different. The OH bond length and IR redshift afford the better measure of hydrogen bond strength.

Sign in / Sign up

Export Citation Format

Share Document