Halogen effect on structure and 13C NMR chemical shift of 3,6-disubstituted-N-alkyl carbazoles

Klaudia Radula-Janik; Teobald Kupka; Krzysztof Ejsmont; Zdzislaw Daszkiewicz; Stephan P. A. Sauer

doi:10.1002/mrc.3992

Halogen effect on structure and ¹³C NMR chemical shift of 3,6-disubstituted-N-alkyl carbazoles

Klaudia Radula-Janik, Teobald Kupka, Krzysztof Ejsmont, Zdzislaw Daszkiewicz, Stephan P. A. Sauer

Department of Chemistry

22 Citations (Scopus)

Abstract

Structures of selected 3,6-dihalogeno-N-alkyl carbazole derivatives were calculated at the B3LYP/6-311++G(3df,2pd) level of theory, and their ¹³C nuclear magnetic resonance (NMR) isotropic shieldings were predicted using density functional theory (DFT). The model compounds contained 9H, N-methyl and N-ethyl derivatives. The relativistic effect of Br and I atoms on nuclear shieldings was modeled using the spin-orbit zeroth-order regular approximation (ZORA) method. Significant heavy atom shielding effects for the carbon atom directly bonded with Br and I were observed (~-10 and ~-30 ppm while the other carbon shifts were practically unaffected). The decreasing electronegativity of the halogen substituent (F, Cl, Br, and I) was reflected in both nonrelativistic and relativistic NMR results as decreased values of chemical shifts of carbon atoms attached to halogen (C3 and C6) leading to a strong sensitivity to halogen atom type at 3 and 6 positions of the carbazole ring. The predicted NMR data correctly reproduce the available experimental data for unsubstituted N-alkylcarbazoles.

Original language	English
Journal	Magnetic Resonance in Chemistry
Volume	51
Issue number	10
Pages (from-to)	630-635
Number of pages	6
ISSN	0749-1581
DOIs	https://doi.org/10.1002/mrc.3992
Publication status	Published - Oct 2013

Keywords

Faculty of Science
NMR
carbazole
chemical shift
relativistic effects
quantum chemistry
computational chemistry
density functional theory
DFT

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10.1002/mrc.3992

Cite this

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title = "Halogen effect on structure and 13C NMR chemical shift of 3,6-disubstituted-N-alkyl carbazoles",

abstract = "Structures of selected 3,6-dihalogeno-N-alkyl carbazole derivatives were calculated at the B3LYP/6-311++G(3df,2pd) level of theory, and their 13C nuclear magnetic resonance (NMR) isotropic shieldings were predicted using density functional theory (DFT). The model compounds contained 9H, N-methyl and N-ethyl derivatives. The relativistic effect of Br and I atoms on nuclear shieldings was modeled using the spin-orbit zeroth-order regular approximation (ZORA) method. Significant heavy atom shielding effects for the carbon atom directly bonded with Br and I were observed (~-10 and ~-30 ppm while the other carbon shifts were practically unaffected). The decreasing electronegativity of the halogen substituent (F, Cl, Br, and I) was reflected in both nonrelativistic and relativistic NMR results as decreased values of chemical shifts of carbon atoms attached to halogen (C3 and C6) leading to a strong sensitivity to halogen atom type at 3 and 6 positions of the carbazole ring. The predicted NMR data correctly reproduce the available experimental data for unsubstituted N-alkylcarbazoles.",

keywords = "Faculty of Science, NMR, carbazole, chemical shift, relativistic effects, quantum chemistry, computational chemistry, density functional theory, DFT",

author = "Klaudia Radula-Janik and Teobald Kupka and Krzysztof Ejsmont and Zdzislaw Daszkiewicz and Sauer, {Stephan P. A.}",

year = "2013",

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language = "English",

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TY - JOUR

T1 - Halogen effect on structure and 13C NMR chemical shift of 3,6-disubstituted-N-alkyl carbazoles

AU - Radula-Janik, Klaudia

AU - Kupka, Teobald

AU - Ejsmont, Krzysztof

AU - Daszkiewicz, Zdzislaw

AU - Sauer, Stephan P. A.

PY - 2013/10

Y1 - 2013/10

N2 - Structures of selected 3,6-dihalogeno-N-alkyl carbazole derivatives were calculated at the B3LYP/6-311++G(3df,2pd) level of theory, and their 13C nuclear magnetic resonance (NMR) isotropic shieldings were predicted using density functional theory (DFT). The model compounds contained 9H, N-methyl and N-ethyl derivatives. The relativistic effect of Br and I atoms on nuclear shieldings was modeled using the spin-orbit zeroth-order regular approximation (ZORA) method. Significant heavy atom shielding effects for the carbon atom directly bonded with Br and I were observed (~-10 and ~-30 ppm while the other carbon shifts were practically unaffected). The decreasing electronegativity of the halogen substituent (F, Cl, Br, and I) was reflected in both nonrelativistic and relativistic NMR results as decreased values of chemical shifts of carbon atoms attached to halogen (C3 and C6) leading to a strong sensitivity to halogen atom type at 3 and 6 positions of the carbazole ring. The predicted NMR data correctly reproduce the available experimental data for unsubstituted N-alkylcarbazoles.

AB - Structures of selected 3,6-dihalogeno-N-alkyl carbazole derivatives were calculated at the B3LYP/6-311++G(3df,2pd) level of theory, and their 13C nuclear magnetic resonance (NMR) isotropic shieldings were predicted using density functional theory (DFT). The model compounds contained 9H, N-methyl and N-ethyl derivatives. The relativistic effect of Br and I atoms on nuclear shieldings was modeled using the spin-orbit zeroth-order regular approximation (ZORA) method. Significant heavy atom shielding effects for the carbon atom directly bonded with Br and I were observed (~-10 and ~-30 ppm while the other carbon shifts were practically unaffected). The decreasing electronegativity of the halogen substituent (F, Cl, Br, and I) was reflected in both nonrelativistic and relativistic NMR results as decreased values of chemical shifts of carbon atoms attached to halogen (C3 and C6) leading to a strong sensitivity to halogen atom type at 3 and 6 positions of the carbazole ring. The predicted NMR data correctly reproduce the available experimental data for unsubstituted N-alkylcarbazoles.

KW - Faculty of Science

KW - NMR

KW - carbazole

KW - chemical shift

KW - relativistic effects

KW - quantum chemistry

KW - computational chemistry

KW - density functional theory

KW - DFT

U2 - 10.1002/mrc.3992

DO - 10.1002/mrc.3992

M3 - Journal article

C2 - 23922027

SN - 0749-1581

VL - 51

SP - 630

EP - 635

JO - Magnetic Resonance in Chemistry

JF - Magnetic Resonance in Chemistry

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ER -