Computational prediction of the 1H and 13C NMR chemical shifts for protonated alkylpyrroles - electron correlation and not solvation is the salvation

Evanildo G. Lacerda, Fadhil S. Kamounah, Kaline coutinho, Stephan P.A. Sauer, Poul Erik Hansen, Ole Hammerich

Publikation: Bidrag til tidsskriftTidsskriftartikelForskningpeer review

Resumé

Prediction of chemical shifts in organic cations is known to be a challenge. In this article we meet this challenge for α-protonated alkylpyrroles, a class of compounds not yet studied in this context, and present a combined experimental and theoretical study of the 13 C and 1 H chemical shifts in three selected pyrroles. We have investigated the importance of the solvation model, basis set, and quantum chemical method with the goal of developing a simple computational protocol, which allows prediction of 13 C and 1 H chemical shifts with sufficient accuracy for identifying such compounds in mixtures. We find that density functional theory with the B3LYP functional is not sufficient for reproducing all 13 C chemical shifts, whereas already the simplest correlated wave function model, Møller-Plesset perturbation theory (MP2), leads to almost perfect agreement with the experimental data. Treatment of solvent effects generally improves the agreement with experiment to some extent and can in most cases be accomplished by a simple polarizable continuum model. The only exception is the NH proton, which requires inclusion of explicit solvent molecules in the calculation.
SprogEngelsk
TidsskriftChemPhysChem
Vol/bind20
Udgave nummer1
Sider78-91
Antal sider14
ISSN1439-4235
DOI
StatusUdgivet - 10 jan. 2019

Emneord

  • protonated pyrroles
  • calculation of nuclear shieldings

Citer dette

Lacerda, Evanildo G. ; Kamounah, Fadhil S. ; coutinho, Kaline ; Sauer, Stephan P.A. ; Hansen, Poul Erik ; Hammerich, Ole. / Computational prediction of the 1H and 13C NMR chemical shifts for protonated alkylpyrroles - electron correlation and not solvation is the salvation. I: ChemPhysChem. 2019 ; Bind 20, Nr. 1. s. 78-91.
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abstract = "Prediction of chemical shifts in organic cations is known to be a challenge. In this article we meet this challenge for α-protonated alkylpyrroles, a class of compounds not yet studied in this context, and present a combined experimental and theoretical study of the 13 C and 1 H chemical shifts in three selected pyrroles. We have investigated the importance of the solvation model, basis set, and quantum chemical method with the goal of developing a simple computational protocol, which allows prediction of 13 C and 1 H chemical shifts with sufficient accuracy for identifying such compounds in mixtures. We find that density functional theory with the B3LYP functional is not sufficient for reproducing all 13 C chemical shifts, whereas already the simplest correlated wave function model, M{\o}ller-Plesset perturbation theory (MP2), leads to almost perfect agreement with the experimental data. Treatment of solvent effects generally improves the agreement with experiment to some extent and can in most cases be accomplished by a simple polarizable continuum model. The only exception is the NH proton, which requires inclusion of explicit solvent molecules in the calculation.",
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author = "Lacerda, {Evanildo G.} and Kamounah, {Fadhil S.} and Kaline coutinho and Sauer, {Stephan P.A.} and Hansen, {Poul Erik} and Ole Hammerich",
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Computational prediction of the 1H and 13C NMR chemical shifts for protonated alkylpyrroles - electron correlation and not solvation is the salvation. / Lacerda, Evanildo G.; Kamounah, Fadhil S.; coutinho, Kaline; Sauer, Stephan P.A.; Hansen, Poul Erik; Hammerich, Ole.

I: ChemPhysChem, Bind 20, Nr. 1, 10.01.2019, s. 78-91.

Publikation: Bidrag til tidsskriftTidsskriftartikelForskningpeer review

TY - JOUR

T1 - Computational prediction of the 1H and 13C NMR chemical shifts for protonated alkylpyrroles - electron correlation and not solvation is the salvation

AU - Lacerda, Evanildo G.

AU - Kamounah, Fadhil S.

AU - coutinho, Kaline

AU - Sauer, Stephan P.A.

AU - Hansen, Poul Erik

AU - Hammerich, Ole

PY - 2019/1/10

Y1 - 2019/1/10

N2 - Prediction of chemical shifts in organic cations is known to be a challenge. In this article we meet this challenge for α-protonated alkylpyrroles, a class of compounds not yet studied in this context, and present a combined experimental and theoretical study of the 13 C and 1 H chemical shifts in three selected pyrroles. We have investigated the importance of the solvation model, basis set, and quantum chemical method with the goal of developing a simple computational protocol, which allows prediction of 13 C and 1 H chemical shifts with sufficient accuracy for identifying such compounds in mixtures. We find that density functional theory with the B3LYP functional is not sufficient for reproducing all 13 C chemical shifts, whereas already the simplest correlated wave function model, Møller-Plesset perturbation theory (MP2), leads to almost perfect agreement with the experimental data. Treatment of solvent effects generally improves the agreement with experiment to some extent and can in most cases be accomplished by a simple polarizable continuum model. The only exception is the NH proton, which requires inclusion of explicit solvent molecules in the calculation.

AB - Prediction of chemical shifts in organic cations is known to be a challenge. In this article we meet this challenge for α-protonated alkylpyrroles, a class of compounds not yet studied in this context, and present a combined experimental and theoretical study of the 13 C and 1 H chemical shifts in three selected pyrroles. We have investigated the importance of the solvation model, basis set, and quantum chemical method with the goal of developing a simple computational protocol, which allows prediction of 13 C and 1 H chemical shifts with sufficient accuracy for identifying such compounds in mixtures. We find that density functional theory with the B3LYP functional is not sufficient for reproducing all 13 C chemical shifts, whereas already the simplest correlated wave function model, Møller-Plesset perturbation theory (MP2), leads to almost perfect agreement with the experimental data. Treatment of solvent effects generally improves the agreement with experiment to some extent and can in most cases be accomplished by a simple polarizable continuum model. The only exception is the NH proton, which requires inclusion of explicit solvent molecules in the calculation.

KW - protonated pyrroles

KW - calculation of nuclear shieldings

KW - alkylpyrroles

KW - NMR calculations

KW - MP2

KW - NMR spectroscopy

KW - ab initio calculations

KW - density functional calculations

KW - protonated alkylpyrroles

KW - solvation

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DO - 10.1002/cphc.201801066

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T2 - ChemPhysChem

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SN - 1439-4235

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