/sup 13/C and /sup 15/N chemical shift tensors of para-substituted benzonitriles
The principal elements of the /sup 13/C and /sup 15/N chemical shift tensors of a series of 10 para-substituted benzonitriles, enriched in /sup 15/N, have been determined. For the /sup 15/N case the static powder patterns and spinning sideband methods have been employed and compared. For the /sup 13/C case, the two-dimensional Fourier Transform flipper and spinning sideband methods were employed and compared. Each method suffers from the effects of dipolar interactions with nearby nuclei, especially those that are quadrupolar. No evidence is found for compelling empirical correlations between the individual tensor elements, or such combinations of them as the asymmetry or anisotropy parameters, and traditional chemical reactivity parameters employed in linear free energy relationships. Pople's independent-electron molecular orbital perturbation theory is useful in understanding the gross relationships between chemical structure and chemical shift tensor elements and in explaining why certain tensor elements show the largest or smallest resonance-withdrawing or resonance-donating effects of substituents.
- Research Organization:
- Colorado State Univ., Fort Collins (USA)
- OSTI ID:
- 6046723
- Journal Information:
- J. Phys. Chem.; (United States), Vol. 92:16
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
NITRILES
STRUCTURAL CHEMICAL ANALYSIS
CARBON 13
CHEMICAL SHIFT
EXPERIMENTAL DATA
NITROGEN 15
NMR SPECTRA
NUCLEAR MAGNETIC RESONANCE
POWDERS
CARBON ISOTOPES
DATA
EVEN-ODD NUCLEI
INFORMATION
ISOTOPES
LIGHT NUCLEI
MAGNETIC RESONANCE
NITROGEN ISOTOPES
NUCLEI
NUMERICAL DATA
ODD-EVEN NUCLEI
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
RESONANCE
SPECTRA
STABLE ISOTOPES
400201* - Chemical & Physicochemical Properties