Structural trends of <sup>77</sup>Se<sup>1</sup>H spin–spin coupling constants and conformational behavior of 2‐substituted selenophenes

Rusakov, Yury Yu.; Krivdin, Leonid B.; Sauer, Stephan P. A.; Леванова, Е. П.; Levkovskaya, G. G.

doi:10.1002/mrc.2537

Cited by 78 publications

(86 citation statements)

References 63 publications

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“…As an example, 2 J (Se,H 4a ) ≈ −1 Hz and 2 J (Se,H 4e ) ≈ +30 Hz in 1 , or 3 J (Se,H 4a ) ≈ 1 Hz, whereas 3 J (Se,H 4e ) ≈ 13 Hz in 6 . With our previous results as basis, we expected that these differences were to be accounted for the selenium lone pair effect for geminal couplings and the Karplus‐type relationship for vicinal coupling constants.…”

Section: Resultsmentioning

confidence: 95%

Stereochemical behavior of ⁷⁷Se‐¹H spin‐spin coupling constants in pyrazolyl‐1,3‐diselenanes and 1,2‐diselenolane

Rusakov

Krivdin

Papernaya

et al. 2012

Magnetic Reson in Chemistry

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Conformational study of five derivatives of 2‐(pyrazol‐4‐yl)‐1,3‐diselenane together with related 1,2‐diselenolane in respect to the stereochemical trends of geminal and vicinal 77Se‐1H spin‐spin coupling constants has been carried out by means of high‐level theoretical calculations in combination with experiment. The marked dihedral angle dependences for both types of couplings accounted for the lone pair effect in the case of geminal coupling constants and the Karplus‐type relationship for vicinal couplings have been established, which is of major importance for the stereochemical analysis of saturated selenium containing heterocycles. Copyright © 2012 John Wiley & Sons, Ltd.

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Section: Resultsmentioning

confidence: 95%

Stereochemical behavior of ⁷⁷Se‐¹H spin‐spin coupling constants in pyrazolyl‐1,3‐diselenanes and 1,2‐diselenolane

Rusakov

Krivdin

Papernaya

et al. 2012

Magnetic Reson in Chemistry

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“…This basis set ensures the correct cusp behaviour of the wave function and consequently a very good description of the FC term [20]. The aug-cc-pVTZ-J basis set yields SSCCs close to those obtained with larger basis sets [20,[27][28][29]. This work is based on the indicated B3LYP/aug-cc-pVTZ geometries.…”

Section: Computational Detailsmentioning

confidence: 86%

Assessment of DFT functionals with fluorine–fluorine coupling constants

Vega

Fabián

2015

Molecular Physics

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Density functional theory (DFT) calculations of nuclear magnetic resonance (NMR) spin-spin coupling constants (SSCCs) provide an important contribution for understanding experimentally observed values. It is known that calculated SSCCs using DFT methods correlate well with those experimentally measured. Unlike most of SSCCs, in fluorine compounds, fluorine-fluorine SSCC J FF shows that the Fermi contact (FC) term is not dominant, particularly for J FF in polyfluorinated organic molecules. In order to devise a DFT approach that would correctly reproduce the variation of SSCCs within a series of fluorine compounds, we test several DFT-based approaches, using different exchange and correlation functionals. Isotropic contributions to NMR fluorine-fluorine coupling constants (FC, spin-dipolar, SD, paramagnetic spin-orbit, PSO, and diamagnetic spin-orbit, DSO) have been calculated. Results show that DFT methods give appropriate values for n J FF (n = 4 to 7), while for geminal and vicinal J FF present large deviations from experimental values. For the latter SSCCs ( 2 J FF and 3 J FF ), the four contributions (FC, SD, PSO and DSO) are analysed as a function of the local and nonlocal exchange in 1,1-and 1,2-difluoroethylene. Although FC term is not dominant for these SSCCs, the variation of this contribution with exchange is remarkable. On the other hand, SD and PSO contributions can be suitably computed without and with exact exchange, respectively.

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“…In particular, basis sets describing electron density close to nuclei are essential for reliable prediction of SSCC. Following several test calculations with relatively small basis set we selected the aug‐cc‐pVTZ‐J basis set25–30 for all NMR calculations. This basis set was initially developed as practical compromise between the size and accuracy for prediction of very demanding SSCC parameters in case of molecules containing more than a few atoms as well as for relatively large molecules (using the ‘locally dense basis set approach’).…”

Section: Methodsmentioning

confidence: 99%

Experimental and theoretical NMR and IR studies of the side‐chain orientation effects on the backbone conformation of dehydrophenylalanine residue

Buczek

Ptak

Kupka

et al. 2011

Magnetic Reson in Chemistry

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Conformation of N-acetyl-(E)-dehydrophenylalanine N', N'-dimethylamide (Ac-(E)-ΔPhe-NMe(2)) in solution, a member of (E)-α, β-dehydroamino acids, was studied by NMR and infrared spectroscopy and the results were compared with those obtained for (Z) isomer. To support the spectroscopic interpretation, the Φ, Ψ potential energy surfaces were calculated at the MP2/6-31 + G(d,p) level of theory in chloroform solution modeled by the self-consistent reaction field-polarizable continuum model method. All minima were fully optimized by the MP2 method and their relative stabilities were analyzed in terms of π-conjugation, internal H-bonds and dipole interactions between carbonyl groups. The obtained NMR spectral features were compared with theoretical nuclear magnetic shieldings, calculated using Gauge Independent Atomic Orbitals (GIAO) approach and rescaled to theoretical chemical shifts using benzene as reference. The calculated indirect nuclear spin-spin coupling constants were compared with available experimental parameters.

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Structural trends of ⁷⁷Se¹H spin–spin coupling constants and conformational behavior of 2‐substituted selenophenes

Cited by 78 publications

References 63 publications

Stereochemical behavior of ⁷⁷Se‐¹H spin‐spin coupling constants in pyrazolyl‐1,3‐diselenanes and 1,2‐diselenolane

Stereochemical behavior of ⁷⁷Se‐¹H spin‐spin coupling constants in pyrazolyl‐1,3‐diselenanes and 1,2‐diselenolane

Assessment of DFT functionals with fluorine–fluorine coupling constants

Experimental and theoretical NMR and IR studies of the side‐chain orientation effects on the backbone conformation of dehydrophenylalanine residue

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Structural trends of 77Se1H spin–spin coupling constants and conformational behavior of 2‐substituted selenophenes

Cited by 78 publications

References 63 publications

Stereochemical behavior of 77Se‐1H spin‐spin coupling constants in pyrazolyl‐1,3‐diselenanes and 1,2‐diselenolane

Stereochemical behavior of 77Se‐1H spin‐spin coupling constants in pyrazolyl‐1,3‐diselenanes and 1,2‐diselenolane

Assessment of DFT functionals with fluorine–fluorine coupling constants

Experimental and theoretical NMR and IR studies of the side‐chain orientation effects on the backbone conformation of dehydrophenylalanine residue

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Structural trends of ⁷⁷Se¹H spin–spin coupling constants and conformational behavior of 2‐substituted selenophenes

Stereochemical behavior of ⁷⁷Se‐¹H spin‐spin coupling constants in pyrazolyl‐1,3‐diselenanes and 1,2‐diselenolane

Stereochemical behavior of ⁷⁷Se‐¹H spin‐spin coupling constants in pyrazolyl‐1,3‐diselenanes and 1,2‐diselenolane