Group-theoretical investigation of the tunneling splitting patterns of enolic acetylacetone

Chou, Yung-Ching

doi:10.1016/j.jms.2010.06.009

Cited by 5 publications

(4 citation statements)

References 31 publications

(53 reference statements)

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“…Acetylacetone (AA) can be considered a prototype molecule for studying keto–enol tautomerization: The titles of 654 scientific articles from the time period 1985–2013 contain the word “acetylacetone”. A variety of both experimental − and theoretical − methods have been applied to determine the shape of AA in the gas phase. They lead to contrasting results as to the relative stability of the ketonic and enolic forms, as well as the symmetry ( C s or C 2 v ) of the enolic tautomer.…”

Section: Introductionmentioning

confidence: 99%

Morphing the Internal Dynamics of Acetylacetone by CH₃ → CF₃ Substitutions. The Rotational Spectrum of Trifluoroacetylacetone

et al. 2014

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The rotational spectrum of trifluoroacetylacetone shows that the molecule exists in an enolic C(s) form and displays the features of internal rotations of the CH3 and CF3 groups, whose barriers to internal rotation were determined to be V3 = 379 and 30.8 cm(-1), respectively. Its internal dynamics appears to be intermediate between those of acetylacetone, where proton tunneling and low-barrier internal rotation of the two methyl groups make the spectrum quite complex, and hexafluoroacetylacetone, a perfectly "rigid" molecule on the time scale of microwave spectroscopy.

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Section: Introductionmentioning

confidence: 99%

Morphing the Internal Dynamics of Acetylacetone by CH₃ → CF₃ Substitutions. The Rotational Spectrum of Trifluoroacetylacetone

et al. 2014

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“…7 It highlights a valuable enhancement of the E-A splitting in a methyl torsion by coupling with the H transfer. Theoretical calculations taking into account all the couplings at play in AcAc possibly explain this result, 19 but further theoretical investigations would be necessary for a full understanding.…”

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confidence: 99%

“…In a first approximation, the NSC process mentioned in the introduction is assigned to NSC in m CO hydrogens and is observed due to the thermal relaxation at 3K from E to A states within the m CO group. Due to the presence of the second methyl group, each of these states contains in fact several levels 19 and we will call them pseudo E and A states, noted "A" and "E" respectively. Hence, the observed spectrum is a superposition of two spectra.…”

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confidence: 99%

Large amplitude motions within molecules trapped in solid parahydrogen

Gutiérrez-Quintanilla

Chevalier

Čeponkus

et al. 2018

Faraday Discuss.

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Molecules of the β-diketone and β-dialdehyde families were trapped in solid parahydrogen (pH2) to investigate the vibrational behavior of systems containing an intramolecular hydrogen bond (IHB). In the simplest β-diketone, acetylacetone (AcAc), H transfer related to the IHB is coupled with methyl torsions. In pH2, the study of nuclear spin conversion (NSC) in methyl groups allows the characterisation of the influence of these large amplitude motions on the vibrational modes. The deuteration of the OH group involved in the IHB has important consequences on the vibrational spectrum of the molecule and evidence of NSC in methyl groups is difficult to obtain. In the chlorine derivative (3-chloroacetylacetone), the H-transfer is no longer coupled with methyl torsion, and NSC has undetectable effects on the IR spectrum. A search of H tunnelling splitting in the IR spectra of β-dialdehydes trapped in pH2 was performed. A few modes of 2-chloromalonaldehyde appear as doublets and were assigned to tunnelling levels. The spectroscopic results related to large amplitude motions are detailed and discussed, highlighting puzzling effects.

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“…Historically, the main experimental techniques used to investigate the structure of ACAC and its derivatives have been nuclear magnetic resonance (NMR), − infrared, − and microwave spectroscopy, as well as structural techniques including electron, X-ray, and neutron diffraction. − The general consensus ,, is that the bridging hydrogen in ACAC exists in a double-minimum potential, with the ground state below the maximum and C s symmetry. Another view, based on microwave spectroscopy and one calculation, is that the symmetry is in fact C 2 v . , Theoretical calculations of the ground state of ACAC at different levels of accuracy − ,− assessed the shape of the PES (potential energy surface) with respect to the movement of the enol hydrogen. The most accurate calculations, by the coupled cluster including singles and doubles and perturbative triples [CCSD(T)] method confirmed that the PES can be described as a double well, with the minima corresponding to a C s structure, the H atom forming a bond with either O atom, and a rather low energy barrier .…”

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confidence: 99%

Quantum Effects for a Proton in a Low-Barrier, Double-Well Potential: Core Level Photoemission Spectroscopy of Acetylacetone

Feyer

Coreno

Melandri

et al. 2018

J. Phys. Chem. Lett.

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We have performed core level photoemission spectroscopy of gaseous acetylacetone, its fully deuterated form, and two derivatives, benzoylacetone and dibenzoylmethane. These molecules show intramolecular hydrogen bonds, with a proton located in a double-well potential, whose barrier height is different for the three compounds. This has allowed us to examine the effect of the double-well potential on photoemission spectra. Two distinct O 1s core hole peaks are observed, previously assigned to two chemical states of oxygen. We provide an alternative assignment of the double-peak structure of O 1s spectra by taking full account of the extended nature of the wave function associated with the nuclear motion of the proton, the shape of the ground and final state potentials in which the proton is located, and the nonzero temperature of the samples. The peaks are explained in terms of an unusual Franck-Condon factor distribution.

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Group-theoretical investigation of the tunneling splitting patterns of enolic acetylacetone

Cited by 5 publications

References 31 publications

Morphing the Internal Dynamics of Acetylacetone by CH₃ → CF₃ Substitutions. The Rotational Spectrum of Trifluoroacetylacetone

Morphing the Internal Dynamics of Acetylacetone by CH₃ → CF₃ Substitutions. The Rotational Spectrum of Trifluoroacetylacetone

Large amplitude motions within molecules trapped in solid parahydrogen

Quantum Effects for a Proton in a Low-Barrier, Double-Well Potential: Core Level Photoemission Spectroscopy of Acetylacetone

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Group-theoretical investigation of the tunneling splitting patterns of enolic acetylacetone

Cited by 5 publications

References 31 publications

Morphing the Internal Dynamics of Acetylacetone by CH3 → CF3 Substitutions. The Rotational Spectrum of Trifluoroacetylacetone

Morphing the Internal Dynamics of Acetylacetone by CH3 → CF3 Substitutions. The Rotational Spectrum of Trifluoroacetylacetone

Large amplitude motions within molecules trapped in solid parahydrogen

Quantum Effects for a Proton in a Low-Barrier, Double-Well Potential: Core Level Photoemission Spectroscopy of Acetylacetone

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Product

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Morphing the Internal Dynamics of Acetylacetone by CH₃ → CF₃ Substitutions. The Rotational Spectrum of Trifluoroacetylacetone

Morphing the Internal Dynamics of Acetylacetone by CH₃ → CF₃ Substitutions. The Rotational Spectrum of Trifluoroacetylacetone