A strong dependence of the CH 3 internal rotation barrier on conformation in thioacetic acid: Microwave measurements and an energy decomposition analysis

C. J. Smith, Anna K. Huff, Huaiyu Zhang, Yirong Mo, Kenneth R Leopold

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

Rotational spectra of thioacetic acid (CH 3 COSH) have been observed by pulsed-nozzle Fourier transform microwave spectroscopy. Spectroscopic constants are reported for both the syn and anti conformers of the parent species, as well as the 34 S and 13 C carbonyl isotopologues. Transitions arising from the lowest A and E internal rotor states of the methyl group have been observed and analyzed. Experimental values of the three-fold internal rotation barrier, V 3 , for the syn and anti conformers of the parent isotopologue are 76.300(12) and 358.056(51) cm −1 , respectively, indicating a large effect of the S−H orientation on the CH 3 internal rotation potential. M06-2X/6-311+G(d,p) calculations are in good agreement with these results. The block localized energy decomposition method has been applied to understand the origins of this strong dependence of V 3 on conformation. The results indicate that π conjugation from the SH to the carbonyl group and steric repulsion between the SH and the methyl group in the anti form are main contributors to the difference.

Original languageEnglish (US)
Article number134302
JournalJournal of Chemical Physics
Volume150
Issue number13
DOIs
StatePublished - Apr 7 2019

Fingerprint

Microwave measurement
Conformations
Microwave spectroscopy
methylidyne
Decomposition
decomposition
microwaves
acids
Nozzles
Fourier transforms
Rotors
rotational spectra
conjugation
nozzles
rotors
energy
spectroscopy
thioacetic acid

PubMed: MeSH publication types

  • Journal Article

Cite this

A strong dependence of the CH 3 internal rotation barrier on conformation in thioacetic acid : Microwave measurements and an energy decomposition analysis. / Smith, C. J.; Huff, Anna K.; Zhang, Huaiyu; Mo, Yirong; Leopold, Kenneth R.

In: Journal of Chemical Physics, Vol. 150, No. 13, 134302, 07.04.2019.

Research output: Contribution to journalArticle

@article{6c710d01aaf6435091e43fbd4597a19a,
title = "A strong dependence of the CH 3 internal rotation barrier on conformation in thioacetic acid: Microwave measurements and an energy decomposition analysis",
abstract = "Rotational spectra of thioacetic acid (CH 3 COSH) have been observed by pulsed-nozzle Fourier transform microwave spectroscopy. Spectroscopic constants are reported for both the syn and anti conformers of the parent species, as well as the 34 S and 13 C carbonyl isotopologues. Transitions arising from the lowest A and E internal rotor states of the methyl group have been observed and analyzed. Experimental values of the three-fold internal rotation barrier, V 3 , for the syn and anti conformers of the parent isotopologue are 76.300(12) and 358.056(51) cm −1 , respectively, indicating a large effect of the S−H orientation on the CH 3 internal rotation potential. M06-2X/6-311+G(d,p) calculations are in good agreement with these results. The block localized energy decomposition method has been applied to understand the origins of this strong dependence of V 3 on conformation. The results indicate that π conjugation from the SH to the carbonyl group and steric repulsion between the SH and the methyl group in the anti form are main contributors to the difference.",
author = "Smith, {C. J.} and Huff, {Anna K.} and Huaiyu Zhang and Yirong Mo and Leopold, {Kenneth R}",
year = "2019",
month = "4",
day = "7",
doi = "10.1063/1.5087718",
language = "English (US)",
volume = "150",
journal = "Journal of Chemical Physics",
issn = "0021-9606",
publisher = "American Institute of Physics Publising LLC",
number = "13",

}

TY - JOUR

T1 - A strong dependence of the CH 3 internal rotation barrier on conformation in thioacetic acid

T2 - Microwave measurements and an energy decomposition analysis

AU - Smith, C. J.

AU - Huff, Anna K.

AU - Zhang, Huaiyu

AU - Mo, Yirong

AU - Leopold, Kenneth R

PY - 2019/4/7

Y1 - 2019/4/7

N2 - Rotational spectra of thioacetic acid (CH 3 COSH) have been observed by pulsed-nozzle Fourier transform microwave spectroscopy. Spectroscopic constants are reported for both the syn and anti conformers of the parent species, as well as the 34 S and 13 C carbonyl isotopologues. Transitions arising from the lowest A and E internal rotor states of the methyl group have been observed and analyzed. Experimental values of the three-fold internal rotation barrier, V 3 , for the syn and anti conformers of the parent isotopologue are 76.300(12) and 358.056(51) cm −1 , respectively, indicating a large effect of the S−H orientation on the CH 3 internal rotation potential. M06-2X/6-311+G(d,p) calculations are in good agreement with these results. The block localized energy decomposition method has been applied to understand the origins of this strong dependence of V 3 on conformation. The results indicate that π conjugation from the SH to the carbonyl group and steric repulsion between the SH and the methyl group in the anti form are main contributors to the difference.

AB - Rotational spectra of thioacetic acid (CH 3 COSH) have been observed by pulsed-nozzle Fourier transform microwave spectroscopy. Spectroscopic constants are reported for both the syn and anti conformers of the parent species, as well as the 34 S and 13 C carbonyl isotopologues. Transitions arising from the lowest A and E internal rotor states of the methyl group have been observed and analyzed. Experimental values of the three-fold internal rotation barrier, V 3 , for the syn and anti conformers of the parent isotopologue are 76.300(12) and 358.056(51) cm −1 , respectively, indicating a large effect of the S−H orientation on the CH 3 internal rotation potential. M06-2X/6-311+G(d,p) calculations are in good agreement with these results. The block localized energy decomposition method has been applied to understand the origins of this strong dependence of V 3 on conformation. The results indicate that π conjugation from the SH to the carbonyl group and steric repulsion between the SH and the methyl group in the anti form are main contributors to the difference.

UR - http://www.scopus.com/inward/record.url?scp=85063919646&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85063919646&partnerID=8YFLogxK

U2 - 10.1063/1.5087718

DO - 10.1063/1.5087718

M3 - Article

C2 - 30954056

AN - SCOPUS:85063919646

VL - 150

JO - Journal of Chemical Physics

JF - Journal of Chemical Physics

SN - 0021-9606

IS - 13

M1 - 134302

ER -