NMR, MP2 and DFT Study of Thiophenoxyketenimines (o-ThioSchiff bases)

Determination of the preferred form

Bahjat Ali Saeed, Rita Sabah Elias, Fadhil S. Kamounah, Poul Erik Hansen

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

Five new thiophenoxyketinimines have been synthesized. 1 H and 13 C NMR spectra as well as deuterium isotope effects on 13 C chemical shifts are determined, and spectra are assigned. DFT and MP2 calculations of both structures, chemical shifts, and isotope effects on chemical shifts are done. The combined analysis reveals that the compounds are primarily on a zwitterionic form with an NH+ and a S- group and with a little of the neutral form mixed in. Very strong intramolecular hydrogen bonding is found and very high NH chemical shifts are observed. The theoretical calculations show that calculations at the MP2 level are best to obtain correct "C═S" chemical shifts.
Original languageEnglish
JournalMagnetic Resonance in Chemistry
Volume56
Issue number3
Pages (from-to)172-182
Number of pages11
ISSN0749-1581
DOIs
Publication statusPublished - 1 Mar 2018

Keywords

  • isotoope effects
  • DFT calculations
  • Hydrogen bond strength.
  • zwitter ion
  • tautomerism

Cite this

Saeed, Bahjat Ali ; Elias, Rita Sabah ; Kamounah, Fadhil S. ; Hansen, Poul Erik. / NMR, MP2 and DFT Study of Thiophenoxyketenimines (o-ThioSchiff bases) : Determination of the preferred form. In: Magnetic Resonance in Chemistry. 2018 ; Vol. 56, No. 3. pp. 172-182.
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abstract = "Five new thiophenoxyketinimines have been synthesized. 1 H and 13 C NMR spectra as well as deuterium isotope effects on 13 C chemical shifts are determined, and spectra are assigned. DFT and MP2 calculations of both structures, chemical shifts, and isotope effects on chemical shifts are done. The combined analysis reveals that the compounds are primarily on a zwitterionic form with an NH+ and a S- group and with a little of the neutral form mixed in. Very strong intramolecular hydrogen bonding is found and very high NH chemical shifts are observed. The theoretical calculations show that calculations at the MP2 level are best to obtain correct {"}C═S{"} chemical shifts.",
keywords = "MP2 and DFT calculations, zwitter ionic form, isotope effects on chemical shifts, tautomerism, isotoope effects, DFT calculations, Hydrogen bond strength. , zwitter ion, tautomerism",
author = "Saeed, {Bahjat Ali} and Elias, {Rita Sabah} and Kamounah, {Fadhil S.} and Hansen, {Poul Erik}",
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doi = "10.1002/mrc.4677",
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NMR, MP2 and DFT Study of Thiophenoxyketenimines (o-ThioSchiff bases) : Determination of the preferred form. / Saeed, Bahjat Ali; Elias, Rita Sabah; Kamounah, Fadhil S.; Hansen, Poul Erik.

In: Magnetic Resonance in Chemistry, Vol. 56, No. 3, 01.03.2018, p. 172-182.

Research output: Contribution to journalJournal articleResearchpeer-review

TY - JOUR

T1 - NMR, MP2 and DFT Study of Thiophenoxyketenimines (o-ThioSchiff bases)

T2 - Determination of the preferred form

AU - Saeed, Bahjat Ali

AU - Elias, Rita Sabah

AU - Kamounah, Fadhil S.

AU - Hansen, Poul Erik

PY - 2018/3/1

Y1 - 2018/3/1

N2 - Five new thiophenoxyketinimines have been synthesized. 1 H and 13 C NMR spectra as well as deuterium isotope effects on 13 C chemical shifts are determined, and spectra are assigned. DFT and MP2 calculations of both structures, chemical shifts, and isotope effects on chemical shifts are done. The combined analysis reveals that the compounds are primarily on a zwitterionic form with an NH+ and a S- group and with a little of the neutral form mixed in. Very strong intramolecular hydrogen bonding is found and very high NH chemical shifts are observed. The theoretical calculations show that calculations at the MP2 level are best to obtain correct "C═S" chemical shifts.

AB - Five new thiophenoxyketinimines have been synthesized. 1 H and 13 C NMR spectra as well as deuterium isotope effects on 13 C chemical shifts are determined, and spectra are assigned. DFT and MP2 calculations of both structures, chemical shifts, and isotope effects on chemical shifts are done. The combined analysis reveals that the compounds are primarily on a zwitterionic form with an NH+ and a S- group and with a little of the neutral form mixed in. Very strong intramolecular hydrogen bonding is found and very high NH chemical shifts are observed. The theoretical calculations show that calculations at the MP2 level are best to obtain correct "C═S" chemical shifts.

KW - MP2 and DFT calculations

KW - zwitter ionic form

KW - isotope effects on chemical shifts

KW - tautomerism

KW - isotoope effects

KW - DFT calculations

KW - Hydrogen bond strength.

KW - zwitter ion

KW - tautomerism

U2 - 10.1002/mrc.4677

DO - 10.1002/mrc.4677

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EP - 182

JO - Magnetic Resonance in Chemistry

JF - Magnetic Resonance in Chemistry

SN - 0749-1581

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ER -