Intramolecular Hydrogen Bonds and Fermi Resonance in N-Substituted N'-(2-Fluorobenzoyl)thiourea Derivatives

1994 ◽  
Vol 59 (4) ◽  
pp. 951-956 ◽  
Author(s):  
Oľga Hritzová ◽  
Dušan Koščík
Keyword(s):  
Hydrogen Bond ◽  
Perturbation Theory ◽  
Hydrogen Bonds ◽  
Bond Strength ◽  
Infrared Spectra ◽  
Fermi Resonance ◽  
Absorption Bands ◽  
Thiourea Derivatives ◽  
Hydrogen Bond Strength ◽  
Intramolecular Hydrogen

The presence of intramolecular NH...O=C bonds was proved in N-substituted N'-(2-fluorobenzoyl)thiourea derivatives by analysis of their infrared spectra. The intramolecular vibrational effects bring about a shift of the ν(NH) vibrational band to lower frequencies to the extent that the band gets into a vicinity to the δ(NH) overtone and Fermi resonance occurs between them. In addition, the ν(NH) vibration is also affected by Fermi resonance with the ν(CO) + δ(NH) combination. Double absorption bands were observed in the ν(CO) region for some of the derivatives. Based on perturbation theory applied to three-level interactions and using the Langseth and Lord equations, the band frequencies corrected for Fermi resonance were calculated and the hydrogen bond strength was examined in the compounds studied.

Non-covalent interactions in molecular systems: thermodynamic evaluation of the hydrogen bond strength in aminoalcohols

2021 ◽  
Author(s):  
Riko Siewert ◽  
Ralf Ludwig ◽  
Sergey P. Verevkin
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonds ◽  
Bond Strength ◽  
Functional Groups ◽  
Thermodynamic Evaluation ◽  
Molecular Systems ◽  
Hydrogen Bond Strength ◽  
Non Covalent Interactions ◽  
Intramolecular Hydrogen ◽  
Covalent Interactions

In molecules with two functional groups that form hydrogen bonds, the strength of intramolecular hydrogen bonds does not depend significantly on the structure.

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.

Intramolecular Hydrogen Bond Strength and pKaDetermination ofN,N‘-Disubstituted Imidazole-4,5-dicarboxamides

2005 ◽  
Vol 7 (1) ◽  
pp. 135-138 ◽  
Author(s):  
Jeremy R. Rush ◽  
Stacey L. Sandstrom ◽  
Jianqing Yang ◽  
Rebecca Davis ◽  
Om Prakash ◽  
...  
Keyword(s):  
Hydrogen Bond ◽  
Bond Strength ◽  
Intramolecular Hydrogen Bond ◽  
Hydrogen Bond Strength ◽  
Intramolecular Hydrogen

Solvent effects on the infrared spectra of anilines. VII. 2-Substituted 4-nitroanilines

1970 ◽  
Vol 23 (5) ◽  
pp. 947 ◽  
Author(s):  
LK Dyall
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonds ◽  
Infrared Spectra ◽  
Solvent Effects ◽  
Intermolecular Hydrogen Bond ◽  
Lone Pair ◽  
Acceptor Molecule ◽  
Intramolecular Hydrogen Bonds ◽  
Intramolecular Hydrogen ◽  
Ortho Substituent

Measurements of N-H stretching frequencies of 4-nitroanilines in the presence of hydrogen bond acceptors show that the ease of forming a second intermolecular hydrogen bond in the presence of an ortho substituent decreases in the order hydrogen > methyl > bromo, methoxyl > nitro. This order demonstrates the importance of repulsions between lone pair orbitals on the ortho substituent and the acceptor molecule. Weak intramolecular hydrogen bonds are detected in 2-iodo- and 2-bromo-aniline, and such bonds can be strengthened by introduction of a 4-nitro substituent.

Near-infrared spectra of Ba(NO2)2•X2O (X = H,D) at 10 K. A local-mode approach

1997 ◽  
Vol 75 (8) ◽  
pp. 1099-1105 ◽  
Author(s):  
Ian M. Walker ◽  
Paul J. McCarthy
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonds ◽  
Infrared Spectra ◽  
Near Infrared ◽  
Fermi Resonance ◽  
Strong Hydrogen Bond ◽  
Local Mode ◽  
Morse Oscillator ◽  
Near Infrared Spectra ◽  
Bifurcated Hydrogen Bond

The fundamental and overtone vibrational spectra of Ba(NO2)2•X2O (X=H,D) have been interpreted using the local mode model. The calculated parameters are consistent with the structure, which has one strong hydrogen bond and one weak bifurcated hydrogen bond. Evidence for Fermi resonance between stretch and bend features having similar energies is discussed. Evidence for the breakdown of the simple Morse oscillator model, which was quite successful for [Formula: see text] hydrogen bonds, is also presented. Keywords: overtone, spectra, near-infrared, hydrates, local-mode model.

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