The halogen effect on the <sup>13</sup>C NMR chemical shift in substituted benzenes

Viesser, Renan V.; Ducati, Lucas C.; Tormena, Cláudio F.; Autschbach, Jochen

doi:10.1039/c8cp01249k

Cited by 40 publications

(35 citation statements)

References 30 publications

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“…The calculations were performed within two schemes, namely using full ZORA Hamiltonian (SO‐ZORA), and the scalar relativistic ZORA Hamiltonian (SR‐ZORA) . The paramagnetic and SO contributions are printed in ADF in the conjoint form, because they both involve the response of the ground state to the presence of the external field, and because there are paramagnetic/SO cross terms in the shielding tensor description . So, in this work, the SO contributions are given as the differences of the “paramagnetic + SO” contributions in SO‐ZORA calculations and those ones obtained from separate SR‐ZORA calculations.…”

Section: Computational Detailssupporting

confidence: 71%

Long‐range relativistic heavy atom effect on ¹H NMR chemical shifts of selenium‐ and tellurium‐containing compounds

Rusakov

Rusakova

2018

Int J of Quantum Chemistry

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Previously unknown manifestation of heavy atom effect on the NMR chemical shifts of βand γ-protons initiated by the relativistic effects of the tellurium and selenium atoms has been investigated in the representative series of selenium-and tellurium-containing compounds. To approve the four-component density functional approach to be the appropriate tool for the investigation of the heavy atom on light atom effect (HALA), the benchmark calculations of the proton chemical shifts have been performed at the CCSD level using comprehensively chosen locally dense basis set with taking into account solvent, vibrational, and relativistic corrections.A good agreement with the experimental data was achieved. The magnitudes of the relativistic HALA corrections to βand γ-proton chemical shifts were found to vary in a wide range, namely from −3.08 ppm for the γ-proton of methyltelluraldehyde to 14.51 ppm for β-proton in benzotelluraldehyde. K E Y W O R D Schalcogens, 1 H NMR, HALA, relativistic effects | INTRODUCTIONAt the present day 1 H NMR spectroscopy plays a major role in the identification and structural elucidation of organic and organometallic compounds. Proton nucleus has very high intrinsic NMR sensitivity due to the significant natural abundance (>99.9%) of the 1 H hydrogen isotopes and a very high gyromagnetic ratio.Thus, proton NMR spectroscopy represents the most straightforward way of receiving structural information, even for the most problematic cases, when, for example, the concentration of a sample is very low.With the growth of computational capacities theoretical modeling of the proton NMR spectra (chemical shifts and spin-spin coupling constants) has become the one of the most powerful supplementary tools for solving structures in proton NMR spectroscopy. As a consequence, the accuracy of prediction of 1 H NMR chemical shifts and spin-spin coupling constants involving proton nuclei is of utmost importance at the present time.When treating the molecules, containing one or more heavy elements, not necessarily located in close vicinity to NMR protons under study, relativistic effects might come into play. The omission of the relativistic effects when modeling the 1 H NMR spectra of molecules containing heavy atoms usually results in the erroneous predictions, sometimes not even falling into the expected range. Thus, an influence of the relativistic effects on the 1 H NMR spectral parameters is one of the most important accuracy factors, which ought to be considered when dealing with the compounds containing heavy elements. An influence of the relativistic effects initiated by the presence of heavy atom (HA) on the nuclear shielding of light atom (LA) or spin-spin coupling constant between two LAs is called as relativistic HALA effect.It has been noticed that 1 H NMR chemical shifts are highly sensitive to the presence of heavy atoms. [1][2][3][4][5][6][7][8][9][10] At the first time HALA effect on proton NMR shielding constants was investigated as earlier as in the beginning of 1970s in hydrogen halides by ...

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Section: Computational Detailssupporting

confidence: 71%

Long‐range relativistic heavy atom effect on ¹H NMR chemical shifts of selenium‐ and tellurium‐containing compounds

Rusakov

Rusakova

2018

Int J of Quantum Chemistry

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“…Relativistic effects in NMR chemical shifts and spinspin coupling constants known as "Heavy Atom on Light Atom" (HALA) effects were evaluated in a great number of molecules containing "heavy" elements, see some salient earlier publications [117][118][119][120][121][122][123][124][125][126] together with some more recent and most recent ones [127][128][129][130][131][132][133][134][135][136][137][138][139][140][141][142][143][144][145] and many other related papers, [146][147][148][149][150][151][152][153][154][155] which are not cited herewith in full in view of their multiplicity.…”

Section: Figurementioning

confidence: 99%

Computational ¹H NMR: Part 1. Theoretical background

Krivdin

2019

Magnetic Reson in Chemistry

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This is the first one of the three closely interrelated reviews to be published in Magnetic Resonance in Chemistry dealing with accordingly theoretical background, chemical applications, and biochemical studies of and by means of computational 1H NMR. Presented in the first part of the review is a general outline of the modern theoretical methods and accuracy factors of computational 1H NMR involving locally dense basis set schemes, solvent effects, vibrational corrections, and relativistic effects performed at the density functional theory and/or nonempirical levels. This review is dedicated to Prof. Stephan Sauer in view of his invaluable contribution to the field of computational nuclear magnetic resonance.

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“…Interpretation of σ para is more complex than σ dia because the paramagnetic mechanism involves magnetic coupling of occupied and unoccupied orbitals. As several articles deeply describe the theory of σ para , we omitted a detailed description in the present work. However, it is important to mention that the magnitude of σ para (sign is usually negative) depends on the strength of the magnetic coupling and the energy gap between coupled orbitals.…”

Section: Resultsmentioning

confidence: 99%

“…Several works show that the δ 13 C depends on how the electronic system responds to the magnetic field; therefore, a more complex explanation is required to clarify the anion behaviour. Thus, the present study aims to demystify the deshielding effect on CF 3 − by determining the involved shielding mechanisms as well as the role of each orbital through density functional theory calculations.…”

Section: Introductionmentioning

confidence: 99%

Counterintuitive deshielding on the ¹³C NMR chemical shift for the trifluoromethyl anion

Viesser

Tormena

2019

Magnetic Reson in Chemistry

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The trifluoromethyl anion (CF 3 − ) displays 13 C NMR chemical shift (175.0 ppm) surprisingly larger than neutral (CHF 3 , 122.2 ppm) and cation (CF 3 + , 150.7 ppm) compounds. This unexpected deshielding effect for a carbanion is investigated by density functional theory calculations and decomposition analyses of the 13 C shielding tensor into localized molecular orbital contributions. The present work determines the shielding mechanisms involved in the observed behaviour of the fluorinated anion species, shedding light on the experimental NMR data and demystify the classical correlation between electron density and NMR chemical shift. The presence of fluorine atoms induces the carbon lone pair to create a paramagnetic shielding on the carbon nucleus.

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The halogen effect on the ¹³C NMR chemical shift in substituted benzenes

Cited by 40 publications

References 30 publications

Long‐range relativistic heavy atom effect on ¹H NMR chemical shifts of selenium‐ and tellurium‐containing compounds

Long‐range relativistic heavy atom effect on ¹H NMR chemical shifts of selenium‐ and tellurium‐containing compounds

Computational ¹H NMR: Part 1. Theoretical background

Counterintuitive deshielding on the ¹³C NMR chemical shift for the trifluoromethyl anion

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The halogen effect on the 13C NMR chemical shift in substituted benzenes

Cited by 40 publications

References 30 publications

Long‐range relativistic heavy atom effect on 1H NMR chemical shifts of selenium‐ and tellurium‐containing compounds

Long‐range relativistic heavy atom effect on 1H NMR chemical shifts of selenium‐ and tellurium‐containing compounds

Computational 1H NMR: Part 1. Theoretical background

Counterintuitive deshielding on the 13C NMR chemical shift for the trifluoromethyl anion

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Product

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The halogen effect on the ¹³C NMR chemical shift in substituted benzenes

Long‐range relativistic heavy atom effect on ¹H NMR chemical shifts of selenium‐ and tellurium‐containing compounds

Long‐range relativistic heavy atom effect on ¹H NMR chemical shifts of selenium‐ and tellurium‐containing compounds

Computational ¹H NMR: Part 1. Theoretical background

Counterintuitive deshielding on the ¹³C NMR chemical shift for the trifluoromethyl anion