The first experimental observation of the higher-energy trans conformer of trifluoroacetic acid

Apóstolo, Rui F. G.; Bazsó, Gábor; Bento, Ricardo Ferreira; Tarczay, György; Fausto, Rui

doi:10.1016/j.molstruc.2016.06.077

Cited by 19 publications

(10 citation statements)

References 59 publications

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“…This provides some predictive power as to when to expect tunneling control to be operative within a series of closely related starting materials . This conclusion is also well supported by the stereoelectronic effects on the tunneling rotamerizations of carboxylic acids …”

Section: Width Trumps Height: Tunneling Control At Workmentioning

confidence: 99%

Tunneling Control of Chemical Reactions: The Third Reactivity Paradigm

2017

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This Perspective describes the emergence of tunneling control as a new reactivity paradigm in chemistry. The term denotes a tunneling reaction that passes through a high but narrow potential energy barrier, leading to formation of a product that would be disfavored if the reaction proceeded by passage over kinetic barriers rather than through them. This reactivity paradigm should be considered along with thermodynamic and kinetic control as a factor that can determine which of two or more possible products is likely to be the one obtained. Tunneling control is a concept that can provide a deep and detailed understanding of a variety of reactions that undergo facile (and possibly unrecognized) tunneling.

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Section: Width Trumps Height: Tunneling Control At Workmentioning

confidence: 99%

Tunneling Control of Chemical Reactions: The Third Reactivity Paradigm

2017

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“…Substituent effects have been shown to affect tunneling rates before, most prominently in systematic studies on carboxylic acids [54–61] and highly reactive hydroxycarbenes [62–69] . In hydroxycarbenes +I‐donating substituents like methyl result in reduced tunneling half‐lives for [1,2]H‐shifts towards the corresponding aldehyde [69] .…”

Section: Resultsmentioning

confidence: 99%

Characterization of the Simplest Thiolimine: The Higher Energy Tautomer of Thioformamide

Bernhardt

Dressler

Eckhardt

et al. 2021

Chemistry A European J

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As sulfur‐containing organic molecules thioamides and their isomers are conceivable intermediates in prebiotic chemistry, for example, in the formation of amino acids and thiazoles and resemble viable candidates for detection in interstellar media. Here, we report the characterization of parent thioformamide in the solid state via single‐crystal X‐ray diffraction and its photochemical interconversion to its hitherto unreported higher energy tautomer thiolimine in inert argon and dinitrogen matrices. Upon photogeneration, four conformers of thiolimine form, whose ratio depends on the employed wavelength. One of these conformers interconverts due to quantum mechanical tunneling with a half‐life of 30–45 min in both matrix materials at 3 and 20 K. A spontaneous reverse reaction from thiolimine to thioformamide is not observed. To support our experimental findings, we explored the potential energy surface of the system at the AE‐CCSD(T)/aug‐cc‐pCVTZ level of theory and computed tunneling half‐lives with the CVT/SCT approach applying DFT methods.

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“…The excellent reproduction of the experimental data by the calculations shall be highlighted, because frequently the DFT method does not describe hydrogen bonding precisely, which is an essential intramolecular interaction in the case of the experimentally-relevant conformer of the studied molecule. Nevertheless, the functional/basis set used in the present study has been shown to be reliable for infrared spectra predictions for many other intramolecularly-bonded molecules formed exclusively by atoms of the first and second row of the periodic table [26][27][28]. In here, only the assignments for the most prominent characteristic vibrations of PHN will be briefly addressed.…”

Section: Infrared Spectra Of Matrix-isolated Phnmentioning

confidence: 96%

Infrared Spectrum and UV-Induced Photochemistry of Matrix-Isolated Phenyl 1-Hydroxy-2-Naphthoate

et al. 2021

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The conformational stability, infrared spectrum, and photochemistry of phenyl 1-hydroxy-2-naphthoate (PHN) were studied by matrix isolation infrared spectroscopy and theoretical computations performed at the DFT(B3LYP)/6-311++G(d,p) level of theory. The main intramolecular interactions determining the relative stability of seven conformers of the molecule were evaluated. According to the calculations, the twofold degenerated O–H···O=C intramolecularly hydrogen-bonded conformer with the phenyl ring ester group ±68.8° out of the plane of the substituted naphtyl moiety is the most stable conformer of the molecule. This conformer is considerably more stable than the second most stable form (by ~15 kJ mol−1), in which a weaker O–H···O–C intramolecular hydrogen bond exists. The compound was isolated in cryogenic argon and N2 matrices, and the conformational composition in the matrices was investigated by infrared spectroscopy. In agreement with the predicted relative energies of the conformers, the analysis of the spectra indicated that only the most stable conformer of PHN was present in the as-deposited matrices. The matrices were then irradiated at various wavelengths by narrowband tunable UV light within the 331.7–235.0 nm wavelength range. This resulted in the photodecarbonylation of PHN, yielding 2-phenoxynaphthalen-1-ol, together with CO. The extension of the decarbonylation was found to depend on the excitation wavelength.

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The first experimental observation of the higher-energy trans conformer of trifluoroacetic acid

Cited by 19 publications

References 59 publications

Tunneling Control of Chemical Reactions: The Third Reactivity Paradigm

Tunneling Control of Chemical Reactions: The Third Reactivity Paradigm

Characterization of the Simplest Thiolimine: The Higher Energy Tautomer of Thioformamide

Infrared Spectrum and UV-Induced Photochemistry of Matrix-Isolated Phenyl 1-Hydroxy-2-Naphthoate

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