ISSN:
0570-0833
Keywords:
Relaxation
;
Mobility
;
13C NMR spectroscopy
;
Chemistry
;
General Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
While the chemical shifts and coupling constants of 13C NMR belong to the most powerful tools available to the organic chemist for the solution of structural problems, increasing interest is being shown in 13C spin-lattice relaxation times T1 as structural parameters. Together with the nuclear Overhauser effects arising by proton decoupling of 13C NMR spectra, the T1 values of 13C nuclei in a molecule permit conclusions to be drawn with regard to relaxation mechanisms. They reflect the inter- and intramolecular mobility of a molecule, and thus complement the results of temperature-dependent NMR spectroscopy. The T1 differences within a molecule show, for instance, whether the molecular motion is anisotropic in solution, whether the internal motion of groups is subject to steric hindrance, the extent to which strong intermolecular or interionic interactions affect the flexibility of the molecule, and which parts of the molecule are rigid and which are flexible. Finally, differences between the T1 values measured for the 13C nuclei of a molecule frequently provide a reliable aid in the assignment of 13C NMR spectra, particularly in cases of signal crowding and multiplet overlapping.
Additional Material:
12 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/anie.197501441
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