Deuterium isotope effects on the carbon-13 chemical shifts in 2-substituted 2-nonbornyl cations

Journal Article · Wed Nov 25 04:00:00 EST 1987 · J. Am. Chem. Soc.; (United States)

DOI:https://doi.org/10.1021/ja00258a003· OSTI ID:5674496

Servis, K L; Domenick, R L; Forsyth, D A; Pan, Y

Deuterium isotope effects on /sup 13/C chemical shifts have been examined as a function of location of deuterium in the C/sub 3/-exo or C/sub 3/-endo positions and as a function of increasing electron demand in the series 2-norbornanone, 2-aryl-2-nonbornyl cations, and 2-methyl-2-norbornyl cation. Comparison with isotope shifts in 2-aryl-2-propyl cations demonstrates a change in the type of response to isotopic perturbation in 2-aryl-2-norbornyl cations as electron demand increases. The results are consistent with the onset of sigma-bridging as electron demand increases. The observed isotope shift at a cation center is suggested to be a sum of contributions from a small upfield shift due to perturbation of the sigma-framework (inductive-type perturbation), a downfield shift due to perturbation of hyperconjugation, and a potentially large upfield shift from perturbation of three-center, two-electron bonding. NMR isotope shifts may be a particularly sensitive probe of sigma-bridging because of the vibrational origin of the isotope effect.

• Research Organization: Univ. of Southern California, Los Angeles
• OSTI ID: 5674496
• Journal Information: J. Am. Chem. Soc.; (United States), Journal Name: J. Am. Chem. Soc.; (United States) Vol. 109:24; ISSN JACSA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400202* -- Isotope Effects
Isotope Exchange
& Isotope Separation
ALCOHOLS
CARBON 13
CARBON ISOTOPES
CATIONS
CHARGED PARTICLES
CHEMICAL SHIFT
DATA
DEUTERIUM
DEUTERIUM COMPOUNDS
EVEN-ODD NUCLEI
EXPERIMENTAL DATA
HYDROGEN COMPOUNDS
HYDROGEN ISOTOPES
HYDROXY COMPOUNDS
INFORMATION
IONS
ISOTOPE EFFECTS
ISOTOPE ENRICHED MATERIALS
ISOTOPES
KETONES
LIGHT NUCLEI
MAGNETIC RESONANCE
MATERIALS
NMR SPECTRA
NUCLEAR MAGNETIC RESONANCE
NUCLEI
NUMERICAL DATA
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
RESONANCE
SPECTRA
SPECTRAL SHIFT
STABLE ISOTOPES