Absolute Signs of Indirect Nuclear Spin-Spin Coupling Constants

Bernheim, R. A.; Lavery, B. J.

doi:10.1021/ja00981a052

Cited by 44 publications

(17 citation statements)

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“…Two or more sets of measurements on a given sample gave an average error of less than 0.02 Hz. The partial decoupling experiments show that 2J(C,F), 3J(C,F), and 'J(C,F) have the same sign as 2J(H,F), which is positive (23). 'J(C,F) is + 1.98(2) Hz and 3J(C,F) is +6.86(1) Hz in 3,5-dichlorobenzyl fluoride in CS2 solution.…”

Section: Resultsmentioning

confidence: 87%

Solvent-induced conformational changes in benzyl fluoride. Long-range C,F; H,H; H,F spin–spin couplings

Schaefer¹,

Peeling²,

Sebastian³

1985

Can. J. Chem.

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The 1H and 19F nmr spectra of benzyl fluoride, although very tightly coupled at 300 MHz, are analyzed for dilute CS2 and acetone solutions. 13C, 19F spin–spin coupling constants for benzyl fluoride in a series of solvents are also measured. Geometry-optimized STO 3G MO computations on benzyl fluoride indicate a small twofold barrier to rotation about the exocyclic C—C bond in the gas phase. All the long-range couplings between 19F and ring protons or carbon-13 nuclei and between methylene and ring protons are consistent with the conclusion that the barrier to internal rotation in benzyl fluoride is small and that the conformation in which the C—F bond lies in a plane perpendicular to the benzene plane is stabilized by 2 kJ/mol in going from CS2 to DMSO or acetone solutions. The solvent dependence of the internal barrier may account for the diversity of conformational conclusions in the literature. Furthermore, it is clear that the internal barrier will depend on the presence of substituents at any site in the ring.

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Section: Resultsmentioning

confidence: 87%

Solvent-induced conformational changes in benzyl fluoride. Long-range C,F; H,H; H,F spin–spin couplings

Schaefer¹,

Peeling²,

Sebastian³

1985

Can. J. Chem.

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“…If one internuclear distance is known, for example from microwave data [4], a value for Saa can be obtained and other internuclear distances can be calculated relative to the assumed distance. According to the usual assumption that the solute molecules orient with their longest geometrical axis parallel to the magnetic field Ssa is positive [5].…”

Section: Tzz (He) + Jzz (S)(he) ]mentioning

confidence: 99%

N.M.R. studies of 3,3,3-trifluoropropyne dissolved in different nematic liquid crystals

et al. 1968

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Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/tmph20 N.M.R. studies of 3,3,3-trifluoropropyne dissolved in different nematic liquid crystalsA high-resolution N.M.R. study of 3,3,3-trifluoropropyne in different liquid crystals is reported. The relative geometry obtained agrees with microwave data. The sign of JIHF) is negative. The anisotropies in fluorine and proton chemical shifts have been measured, and are comparable in magnitude and sign with values previously reported for similar compounds.

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“…The absolute sign of J between two coupled spins can be determined using NMR if the two coupled spins are subject to additional interactions, such as weak residual dipolar coupling in an aligned medium [33].…”

Section: Determining the Sign Of Indirect Spin-spin Coupling Constantmentioning

confidence: 99%

Quantitative analysis of Earth’s field NMR spectra of strongly-coupled heteronuclear systems

Halse

Callaghan

Feland

et al. 2009

Journal of Magnetic Resonance

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Absolute Signs of Indirect Nuclear Spin-Spin Coupling Constants

Cited by 44 publications

References 0 publications

Solvent-induced conformational changes in benzyl fluoride. Long-range C,F; H,H; H,F spin–spin couplings

Solvent-induced conformational changes in benzyl fluoride. Long-range C,F; H,H; H,F spin–spin couplings

N.M.R. studies of 3,3,3-trifluoropropyne dissolved in different nematic liquid crystals

Quantitative analysis of Earth’s field NMR spectra of strongly-coupled heteronuclear systems

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