Vicinal deuterium isotope effects on proton chemical shifts

Saur, W.; Crespi, Henry L.; Katz, Joseph

doi:10.1016/0022-2364(70)90085-5

Cited by 11 publications

(3 citation statements)

References 6 publications

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“…The Δδ phenomenon, known for more than 40 years, − leads to perturbations demonstrated to be essentially linear with increasing deuterium substitution at equivalent positions . The stereochemical aspects of such perturbations for 13 C chemical shifts in D−C−C− 13 C systems have received much attention, − but D−C−C−H fragments have been relatively neglected. Various deuterium-induced chemical shift perturbations for vicinal hydrogens in selectively labeled tert -butylcyclohexanes and cyclohexanes have been reported .…”

Section: Resultsmentioning

confidence: 99%

Vicinal Deuterium Perturbations on Hydrogen NMR Chemical Shifts in Cyclohexanes

et al. 2008

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The substitution of a deuterium for a hydrogen is known to perturb the NMR chemical shift of a neighboring hydrogen atom. The magnitude of such a perturbation may depend on the specifics of bonding and stereochemical relationships within a molecule. For deuterium-labeled cyclohexanes held in a chair conformation at -80 degrees C or lower, all four possible perturbations of H by D as H-C-C-H is changed to D-C-C-H have been determined experimentally, and the variations seen, ranging from 6.9 to 10.4 ppb, have been calculated from theory and computational methods. The predominant physical origins of the NMR chemical shift perturbations in deuterium-labeled cyclohexanes have been identified and quantified. The trends defined by the Delta delta perturbation values obtained through spectroscopic experiments and by theory agree satisfactorily. They do not match the variations typically observed in vicinal J(H-H) coupling constants as a function of dihedral angles.

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Section: Resultsmentioning

confidence: 99%

Vicinal Deuterium Perturbations on Hydrogen NMR Chemical Shifts in Cyclohexanes

et al. 2008

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“…The geometric H/D isotope effect leads to the changes of the electronic structures of proton-donating and proton-accepting moieties and as a result the effect propagates further to a neighboring hydrogen bond, causing its geometry to change as well. The geometric changes manifest themselves as the change in its 1 H-NMR chemical shift, a phenomenon that previously was called "vicinal H/D isotope effect" [16]. After the partial deuteration of the sample the deuterons are distributed among all hydroxyl groups, which results in the coexistence of a number of isotopologs.…”

Section: Partially Deuterated Complexesmentioning

confidence: 99%

“…In our previous works the stoichiometry of the phosphinic and phosphoric acid cyclic trimers has been established by the use of H/D isotope effects on 1 H-NMR chemical shifts: three hydrogen bonds are mutually coupled and deuteration in one of them changes the geometry and, thus, the NMR parameters of the remaining ones. This phenomenon has been previously called "vicinal H/D isotope effects" [16]. The number of such H/D isotope effects allows one to enumerate the coupled hydrogen bonds in a complex; the signs of the H/D isotope effects enable one to distinguish between cooperative and anticooperative coupling schemes [17].…”

Section: Introductionmentioning

confidence: 99%

H/D Isotope Effects on 1H-NMR Chemical Shifts in Cyclic Heterodimers and Heterotrimers of Phosphinic and Phosphoric Acids

et al. 2020

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Hydrogen-bonded heterocomplexes formed by POOH-containing acids (diphenylphosphoric 1, dimethylphosphoric 2, diphenylphosphinic 3, and dimethylphosphinic 4) are studied by the low-temperature (100 K) 1H-NMR and 31P-NMR using liquefied gases CDF3/CDF2Cl as a solvent. Formation of cyclic dimers and cyclic trimers consisting of molecules of two different acids is confirmed by the analysis of vicinal H/D isotope effects (changes in the bridging proton chemical shift, δH, after the deuteration of a neighboring H-bond). Acids 1 and 4 (or 1 and 3) form heterotrimers with very strong (short) H-bonds (δH ca. 17 ppm). While in the case of all heterotrimers the H-bonds are cyclically arranged head-to-tail, ···O=P–O–H···O=P–O–H···, and thus their cooperative coupling is expected, the signs of vicinal H/D isotope effects indicate an effective anticooperativity, presumably due to steric factors: when one of the H-bonds is elongated upon deuteration, the structure of the heterotrimer adjusts by shortening the neighboring hydrogen bonds. We also demonstrate the formation of cyclic tetramers: in the case of acids 1 and 4 the structure has alternating molecules of 1 and 4 in the cycle, while in case of acids 1 and 3 the cycle has two molecules of 1 followed by two molecules of 3.

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