NMR spin–spin coupling constants and hyperconjugative interactions

Contreras, Rubén H.; Suardíaz, Reynier; Pérez, Carolina; Crespo‐Otero, Rachel; Fabián, J. San; Vega, José Manuel García de la

doi:10.1002/qua.22136

Cited by 11 publications

(10 citation statements)

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“…σ→σ*, σ→π*, nx→σ*, nx→π*, hyperconjugation, and homohyperconjugative interactions significantly affect the Fermi contact contribution to the scalar spin–spin coupling constant. Therefore, the C–H coupling constants were used to investigate the stereoelectronic effects [ 64 – 65 ]. The main interactions found by NBO are listed in Supporting Information File 1 .…”

Section: Resultsmentioning

confidence: 99%

Investigation of the role of stereoelectronic effects in the conformation of piperidones by NMR spectroscopy and X-ray diffraction

Garcías-Morales¹,

Ortegón-Reyna²,

Ariza‐Castolo³

2015

Beilstein J. Org. Chem.

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SummaryThis paper reports the synthesis of a series of piperidones 1–8 by the Mannich reaction and analysis of their structures and conformations in solution by NMR and mass spectrometry. The six-membered rings in 2,4,6,8-tetraphenyl-3,7-diazabicyclo[3.3.1]nonan-9-ones, compounds 1 and 2, adopt a chair–boat conformation, while those in 2,4-diphenyl-3-azabicyclo[3.3.1]nonan-9-ones, compounds 3–8, adopt a chair–chair conformation because of stereoelectronic effects. These stereoelectronic effects were analyzed by the 1 J C–H coupling constants, which were measured in the 13C satellites of the 1H NMR spectra obtained with the hetero-dqf pulse sequence. In the solid state, these stereoelectronic effects were investigated by measurement of X-ray diffraction data, the molecular geometry (torsional bond angles and bond distances), and inter- and intramolecular interactions, and by natural bond orbital analysis, which was performed using density functional theory at the ωB97XD/6311++G(d,p) level. We found that one of the main factors influencing the conformational stability of 3–8 is the interaction between the lone-pair electrons of nitrogen and the antibonding sigma orbital of C(7)–Heq (nN→σ*C–H(7)eq), a type of hyperconjugative interaction.

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Section: Resultsmentioning

confidence: 99%

Investigation of the role of stereoelectronic effects in the conformation of piperidones by NMR spectroscopy and X-ray diffraction

Garcías-Morales¹,

Ortegón-Reyna²,

Ariza‐Castolo³

2015

Beilstein J. Org. Chem.

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“…This fact has been recently interpreted as a consequence of hyperconjugative interactions between orbitals of the coupling pathway and those of carbonyl group. 8,23,24 It is also noteworthy that the value of coefficient S 2 is larger than those of S 1 and C 3 (extra coefficient regarding classic Karplus equation) suggesting a more important role in the fitting of truncated Fourier series.…”

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confidence: 96%

“…B3LYP/TZVP level of theory has proved to provide similar results to those of ab initio SOPPA and SOPPA(CCSD) methods with larger basis sets 19 and has been used successfully in the calculations of J and hyperfine couplings. [20][21][22][23][24] (5) The nine sets of coupling constants 3 J XY and the angles from geometry optimizations were used to calculate the six corresponding Fourier coefficients in Eq. (1), solving 6 × 6 system of nonhomogeneous linear equations.…”

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confidence: 99%

Communication: Accurate determination of side-chain torsion angle χ1 in proteins: Phenylalanine residues

Suardíaz

Crespo‐Otero

Pérez

et al. 2011

The Journal of Chemical Physics

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Quantitative side-chain torsion angle χ1 determinations of phenylalanine residues in Desulfovibrio vulgaris flavodoxin are carried out using exclusively the correlation between the experimental vicinal coupling constants and theoretically determined Karplus equations. Karplus coefficients for nine vicinal coupling related with the torsion angle χ1 were calculated using the B3LYP functional and basis sets of different size. Optimized χ1 angles are in outstanding agreement with those previously reported by employing x ray and NMR measurements.

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“…The authors found a relevant contribution from the S 2 term and rather unexpected positive C 1 coefficient. The latter has been interpreted in terms of hyperconjugative interactions [98,100,101].…”

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confidence: 99%

“…In this sense, exploring the dependence of a given J-coupling over the entire range of values of the corresponding dihedral angle can be better achieved using ab initio calculations [24,80,[87][88][89][90][91][92][93][94][95][96][97][98][99][100][101][102][103][104]107,[111][112][113][114][115][116][117][118][119][120][121][122][123]. Whether or not the associated Karplus fit will improve over the empirical ones for structure determination critically depends on the ability of the computational model (i.e.…”

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Dependencies of J-Couplings upon Dihedral Angles on Proteins

Salvador

2014

Annual Reports on NMR Spectroscopy

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This chapter was originally published in the book Annual Reports On NMR Spectroscopy, Vol. 81 published by Elsevier, and the attached copy is provided by Elsevier for the author's benefit and for the benefit of the author's institution, for noncommercial research and educational use including without limitation use in instruction at your institution, sending it to specific colleagues who know you, and providing a copy to your institution's administrator. All other uses, reproduction and distribution, including without limitation commercial reprints, selling or licensing copies or access, or posting on open internet sites, your personal or institution's website or repository, are prohibited. For exceptions, permission may be sought for such use through Elsevier's permissions site at:

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NMR spin–spin coupling constants and hyperconjugative interactions

Cited by 11 publications

References 35 publications

Investigation of the role of stereoelectronic effects in the conformation of piperidones by NMR spectroscopy and X-ray diffraction

Investigation of the role of stereoelectronic effects in the conformation of piperidones by NMR spectroscopy and X-ray diffraction

Communication: Accurate determination of side-chain torsion angle χ1 in proteins: Phenylalanine residues

Dependencies of J-Couplings upon Dihedral Angles on Proteins

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