Evidence for blue-shifting and red-shifting effects in the C2H4···HCF3, C2H3(CH3)···HCF3 and C2H2(CH3)2···HCF3 complexes: π and improper-π hydrogen bonds

Oliveira, Boaz G.; Araújo, Regiane C. M. U.; Ramos, Mozart N.

doi:10.1016/j.theochem.2009.12.032

Cited by 22 publications

(7 citation statements)

References 53 publications

(53 reference statements)

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“…As aforementioned, the p bonds are reduced and strengthened after the formation of the I-IV complexes, but now, the vibration analysis point out slight blue shifts with increasing absorption intensity ratios [73,74]. Bearing in mind that the ethyl cation is a proton donor, the distance shortening reaffirms that pÁÁÁH possesses the same profile observed in a large number of systems stabilized via H-bond [75,76].…”

Section: Structure and Spectrummentioning

confidence: 60%

Quantum chemical studies of non-covalent interactions between the ethyl cation and rare gases

Oliveira¹

2014

Comptes Rendus. Chimie

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Section: Structure and Spectrummentioning

confidence: 60%

Quantum chemical studies of non-covalent interactions between the ethyl cation and rare gases

Oliveira¹

2014

Comptes Rendus. Chimie

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“…17,27 However, some experimental and theoretical results suggest that a red shift effect can be identified in the case of relatively weak interactions between F 3 CH or Cl 3 CH and specific proton acceptors, 19,28 particularly p-electron areas of unsaturated compounds. 29,30 In the present paper, the results of experimental studies of complex formation between Cl 3 CH as a potential ''improper'' proton donor and a set of proton acceptors (B = CH 3 CCH, C 2 H 2 , ClCD 3 , NCCD 3 , and CO) having a p-electron area in the vicinity of the triple CRC bond or an electronegative element of weak to medium electron donor strength are reported. Such a choice suggests the formation of weakly bound complexes characterized by small changes in frequency of the CH stretching vibration and in the C-H bond length of chloroform.…”

Section: Introductionmentioning

confidence: 94%

Strong and weak effects caused by non covalent interactions between chloroform and selected electron donor molecules

Rutkowski

Меликова

Роспенк

et al. 2011

Phys. Chem. Chem. Phys.

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The FTIR spectra of chloroform (Cl(3)CH) in mixtures with various electron donors (B = CH(3)CCH, HCCH, NCCD(3), ClCD(3) and CO) have been studied in liquefied Kr. Spectroscopic evidence of weak H-bond formation has been found. The relative stability of some complexes has been evaluated from temperature studies of integrated intensities of vibrational bands attributed to monomer and complex species. A weak red shift of the stretching vibration of chloroform involved in H-bonding with CH(3)CCH and HCCH having π-electron area was observed. However, in the case of interactions with NCCD(3) and CO, a weak blue shift was detected. In most of the cases, a noticeable increase in the integrated intensity of the CH stretching band was found. Ab initio MP2/6-311++G(2d,2p) a priori counterpoise corrected calculations have been performed for a series of Cl(3)CH and B. Stationary points at the potential energy surface were examined and the structures related to the real minima have been found. The calculations reproduce the majority of experimental results. It has been found that the commonly used correlation between the frequency shift of the CH stretching vibration of the proton donor subunit and the change in CH bond length can fail in the case of the complexes characterized by a weak frequency shift effect.

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“…Historically, the formation of intermolecular or intramolecular hydrogen bonds has been discussed by taking into account the van der Waals radii of the electron donor-acceptor. If we consider this statement [5], the distance values for typical hydrogen bonds should be exactly the same as or shorter than 2.6 Å, of course regarding the F, O and N atoms, or even the π cloud as proton-acceptor centers [13][14][15][16]. In fact, the characterization of hydrogen bonds is not just dependent on structural parameters, actually, the application of quantum mechanical criteria is feasible in this regard.…”

Section: Computational Proceduresmentioning

confidence: 99%

Comparisons between Crystallography Data and Theoretical Parameters and the Formation of Intramolecular Hydrogen Bonds: Benznidazole

2016

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Abstract:The conformational preferences of benznidazole were examined through the application of DFT, PCM and QTAIM calculations, whose results were compared with crystallography data. The geometries were fully optimized with minimum potential energy surface by means of the Relaxed Potential Energy Surface Scan (RPESS) at AM1, followed by the B3LYP/6-311++G(d,p) theoretical level. As a result, the s-cis conformation (1C) was shown to be more stable (4.78 kcal¨mol´1) than s-trans (1T). The Quantum Theory Atoms in Molecules (QTAIM) was applied in order to characterize the (N-H¨¨¨O=N) and (C-H¨¨¨=N) intramolecular hydrogen bonds. The simulation of solvent effect performed by means of the implicit Polarized Continuum Model (PCM) revealed great results, such as, for instance, that the conformation 1W is more stable (23.17 kcal¨mol´1) in comparison to 1C. Our main goal was stressed in the topological description of intramolecular hydrogen bonds in light of the QTAIM approach, as well as in the solvent simulation to accurately obtain an important conformation of benznidazole.

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Evidence for blue-shifting and red-shifting effects in the C2H4···HCF3, C2H3(CH3)···HCF3 and C2H2(CH3)2···HCF3 complexes: π and improper-π hydrogen bonds

Cited by 22 publications

References 53 publications

Quantum chemical studies of non-covalent interactions between the ethyl cation and rare gases

Quantum chemical studies of non-covalent interactions between the ethyl cation and rare gases

Strong and weak effects caused by non covalent interactions between chloroform and selected electron donor molecules

Comparisons between Crystallography Data and Theoretical Parameters and the Formation of Intramolecular Hydrogen Bonds: Benznidazole

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