Methyl tunnelling in acetylacetone

Horsewill, A.J.; Alsanoosi, A. M.; Carlile, C.J.

doi:10.1088/0022-3719/20/31/003

Cited by 18 publications

(8 citation statements)

References 10 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The barrier for methyl rotation of the C8 methyl group (Figure ) in AcAc is calculated to be 1.45 kcal/mol at the MP2(FC)/6-311G(d,p) level . Methyl barrier heights of 0.45 and 1.17 kcal/mol were predicted on the basis of inelastic neutron scattering measurements on solid AcAc and in the range 0.44–1.59 kcal/mol in more recent experiments on the enol tautomer . The potential barriers of the enol tautomer were also sensitive to deuteration of the non-methyl protons .…”

Section: Results and Discussionmentioning

confidence: 91%

“…76 Our finding is in fair agreement with previously determined barrier heights of ∼0.4−1.6 kcal/mol in solid AcAc. 19,65 Methine CH-Stretching Regions. The observed methine CH-stretching overtone transitions of AcAc and HFAA and the local mode parameters obtained from the observed Δv = 2−5 transitions are presented in Table 3.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…In both overtone regions, the methyl band profile is essentially a two-peak structure representing the in- and out-of-plane CH oscillators, and on the basis of this observation, we would expect that the methyl torsional barrier height is greater than 0.7 kcal/mol . Our finding is in fair agreement with previously determined barrier heights of ∼0.4–1.6 kcal/mol in solid AcAc. , …”

Section: Results and Discussionmentioning

confidence: 99%

See 2 more Smart Citations

Infrared and Near-Infrared Spectroscopy of Acetylacetone and Hexafluoroacetylacetone

et al. 2015

View full text Add to dashboard Cite

The infrared and near-infrared spectra of acetylacetone, acetylacetone-d8, and hexafluoroacetylacetone are characterized from experiment and computations at different levels. In the fundamental region, the intramolecular hydrogen bonded OH-stretching transition is clearly observed as a very broad band with substantial structure and located at significantly lower frequency compared to common OH-stretching frequencies. There is no clear evidence for OH-stretching overtone transitions in the near-infrared region, which is dominated by the CH-stretching overtones of the methine and methyl CH bonds. From molecular dynamics (MD) simulations, with a potential energy surface previously validated for tunneling splittings, the infrared spectra are determined and used in assigning the experimentally measured ones. It is found that the simulated spectrum in the region associated with the proton transfer mode is exquisitely sensitive to the height of the barrier for proton transfer. Comparison of the experimental and the MD simulated spectra establishes that the barrier height is around 2.5 kcal/mol, which favorably compares with 3.2 kcal/mol obtained from high-level electronic structure calculations.

show abstract

Section: Results and Discussionmentioning

confidence: 91%

Section: ■ Results and Discussionmentioning

confidence: 99%

Section: Results and Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Infrared and Near-Infrared Spectroscopy of Acetylacetone and Hexafluoroacetylacetone

et al. 2015

View full text Add to dashboard Cite

show abstract

“…For the system that includes two linear O-H-O hydrogen bonds, TPT reaction is described using symmetric (F) and antisymmetric (X) coordinates given by9 Y=r\ + ri~ri-U x = rx -r1 -r3 + r4 (7) where r\ are the O-H bond distances. Two N-H-N fragments are nonlinear in porphyrin (see Figure 3), and four coordinates are required for the description of the plane motion of two protons.…”

Section: Synchronous Versus Asynchronous Two-proton Transfermentioning

confidence: 99%

Two-Dimensional Tunneling: Bifurcations and Competing Trajectories

Benderskiĭ¹,

Grebenshchikov²,

Vetoshkin³

et al. 1994

J. Phys. Chem.

View full text Add to dashboard Cite

“…This material is known to have low hindering potential of threefold symmetry. With INS and NMR methods [12], two A to E tunneling splittings were arrived at: ϳ10 GHz and a few hundred MHz. The level crossing peaks in Fig.…”

mentioning

confidence: 99%

Observation of CH3Tunneling Manifold by Level-Crossing NMR

Choi

Pintar

1996

Phys. Rev. Lett.

View full text Add to dashboard Cite

Rotational tunneling spectra of strongly hindered CH 3 torsional oscillator pairs which do not interact among themselves are reported. These results are obtained by applying the Zeeman-tunneling level matching method in the proton spin rotating frame. Two noninteracting CH 3 particle manifolds explain the observed CH 3 multiquantum transitions driven by intramolecular and͞or intermolecular dipoledipole interactions to first or second order. Level matching resonances indicating that two methyl groups simultaneously undergo a symmetry breaking transition are observed. The dependencies of level-crossing transitions on Zeeman-tunneling mixing time and tilt angle are reported.

show abstract

Methyl tunnelling in acetylacetone

Cited by 18 publications

References 10 publications

Infrared and Near-Infrared Spectroscopy of Acetylacetone and Hexafluoroacetylacetone

Infrared and Near-Infrared Spectroscopy of Acetylacetone and Hexafluoroacetylacetone

Two-Dimensional Tunneling: Bifurcations and Competing Trajectories

Observation of CH3Tunneling Manifold by Level-Crossing NMR

Contact Info

Product

Resources

About