Do the mercaptocarbene (H-C-S-H) and selenocarbene (H-C-Se-H) congeners of hydroxycarbene (H-C-O-H) undergo 1,2-H-tunneling?

János Sarka, A. Császár, Peter R. Schreiner

Research output: Article

8 Citations (Scopus)

Abstract

The principal purpose of this investigation is the determination of the tunneling half-lives of the trans-HCSH → H2CS and the trans-HCSeH → H2CSe unimolecular isomerization reactions at temperatures close to 0 K. To aid these determinations, accurate electronic structure computations were performed, with electron correlation treatments as extensive as CCSDT(Q) and basis sets as large as aug-cc-pCV5Z, for the isomers of [H,H,C,S] and [H,H,C,Se] on their lowest singlet surfaces and for the appropriate transition states yielding structural data for key stationary points characterizing the isomerization reactions. The computational results were subjected to a focal-point analysis (FPA) that yields accurate relative energies with uncertainty estimates. The tunneling half-lives were determined by a simple Eckart-barrier approach and via the more sophisticated though still one-dimensional Wentzel-Kramers- Brillouin (WKB) approximation. Only stationary-point information is needed for the former while an intrinsic reaction path (IRP) is necessary for the latter approach. Both protocols suggest that, unlike for the parent hydroxymethylene (HCOH), at the low temperatures of matrix isolation experiments no tunneling will be observable for the trans-HCSH and trans-HCSeH systems.

Original languageEnglish
Pages (from-to)645-667
Number of pages23
JournalCollection of Czechoslovak Chemical Communications
Volume76
Issue number6
DOIs
Publication statusPublished - 2011

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Isomerization
Electron correlations
Isomers
Electronic structure
Temperature
Experiments
Uncertainty

ASJC Scopus subject areas

  • Chemistry(all)

Cite this

@article{0721fda981be418897ce701722503529,
title = "Do the mercaptocarbene (H-C-S-H) and selenocarbene (H-C-Se-H) congeners of hydroxycarbene (H-C-O-H) undergo 1,2-H-tunneling?",
abstract = "The principal purpose of this investigation is the determination of the tunneling half-lives of the trans-HCSH → H2CS and the trans-HCSeH → H2CSe unimolecular isomerization reactions at temperatures close to 0 K. To aid these determinations, accurate electronic structure computations were performed, with electron correlation treatments as extensive as CCSDT(Q) and basis sets as large as aug-cc-pCV5Z, for the isomers of [H,H,C,S] and [H,H,C,Se] on their lowest singlet surfaces and for the appropriate transition states yielding structural data for key stationary points characterizing the isomerization reactions. The computational results were subjected to a focal-point analysis (FPA) that yields accurate relative energies with uncertainty estimates. The tunneling half-lives were determined by a simple Eckart-barrier approach and via the more sophisticated though still one-dimensional Wentzel-Kramers- Brillouin (WKB) approximation. Only stationary-point information is needed for the former while an intrinsic reaction path (IRP) is necessary for the latter approach. Both protocols suggest that, unlike for the parent hydroxymethylene (HCOH), at the low temperatures of matrix isolation experiments no tunneling will be observable for the trans-HCSH and trans-HCSeH systems.",
keywords = "Ab initio calculations, Carbenes, Eckart barrier, Hydrogen transfer, Mercaptocarbene (HCSH), Selenocarbene (HCSeH), Tunneling, WKB approximation",
author = "J{\'a}nos Sarka and A. Cs{\'a}sz{\'a}r and Schreiner, {Peter R.}",
year = "2011",
doi = "10.1135/cccc2011053",
language = "English",
volume = "76",
pages = "645--667",
journal = "ChemPlusChem",
issn = "2192-6506",
publisher = "Wiley-VCH Verlag",
number = "6",

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TY - JOUR

T1 - Do the mercaptocarbene (H-C-S-H) and selenocarbene (H-C-Se-H) congeners of hydroxycarbene (H-C-O-H) undergo 1,2-H-tunneling?

AU - Sarka, János

AU - Császár, A.

AU - Schreiner, Peter R.

PY - 2011

Y1 - 2011

N2 - The principal purpose of this investigation is the determination of the tunneling half-lives of the trans-HCSH → H2CS and the trans-HCSeH → H2CSe unimolecular isomerization reactions at temperatures close to 0 K. To aid these determinations, accurate electronic structure computations were performed, with electron correlation treatments as extensive as CCSDT(Q) and basis sets as large as aug-cc-pCV5Z, for the isomers of [H,H,C,S] and [H,H,C,Se] on their lowest singlet surfaces and for the appropriate transition states yielding structural data for key stationary points characterizing the isomerization reactions. The computational results were subjected to a focal-point analysis (FPA) that yields accurate relative energies with uncertainty estimates. The tunneling half-lives were determined by a simple Eckart-barrier approach and via the more sophisticated though still one-dimensional Wentzel-Kramers- Brillouin (WKB) approximation. Only stationary-point information is needed for the former while an intrinsic reaction path (IRP) is necessary for the latter approach. Both protocols suggest that, unlike for the parent hydroxymethylene (HCOH), at the low temperatures of matrix isolation experiments no tunneling will be observable for the trans-HCSH and trans-HCSeH systems.

AB - The principal purpose of this investigation is the determination of the tunneling half-lives of the trans-HCSH → H2CS and the trans-HCSeH → H2CSe unimolecular isomerization reactions at temperatures close to 0 K. To aid these determinations, accurate electronic structure computations were performed, with electron correlation treatments as extensive as CCSDT(Q) and basis sets as large as aug-cc-pCV5Z, for the isomers of [H,H,C,S] and [H,H,C,Se] on their lowest singlet surfaces and for the appropriate transition states yielding structural data for key stationary points characterizing the isomerization reactions. The computational results were subjected to a focal-point analysis (FPA) that yields accurate relative energies with uncertainty estimates. The tunneling half-lives were determined by a simple Eckart-barrier approach and via the more sophisticated though still one-dimensional Wentzel-Kramers- Brillouin (WKB) approximation. Only stationary-point information is needed for the former while an intrinsic reaction path (IRP) is necessary for the latter approach. Both protocols suggest that, unlike for the parent hydroxymethylene (HCOH), at the low temperatures of matrix isolation experiments no tunneling will be observable for the trans-HCSH and trans-HCSeH systems.

KW - Ab initio calculations

KW - Carbenes

KW - Eckart barrier

KW - Hydrogen transfer

KW - Mercaptocarbene (HCSH)

KW - Selenocarbene (HCSeH)

KW - Tunneling

KW - WKB approximation

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U2 - 10.1135/cccc2011053

DO - 10.1135/cccc2011053

M3 - Article

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JO - ChemPlusChem

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SN - 2192-6506

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