Correlation of the C–H Stretching Force Constant with the Nuclear 13C–H Coupling Constant
- 15 March 1966
- journal article
- Published by AIP Publishing in The Journal of Chemical Physics
- Vol. 44 (6) , 2238-2243
- https://doi.org/10.1063/1.1727028
Abstract
The characteristic CH3 stretching frequencies in a number of selected compounds in carbon tetrachloride solution have been measured and compared with the nuclear 13C–H scalar coupling constant, J. The correlation provides a basis for expressing the C–H stretching force constant Kr in terms of J. Using a modified valence-force-field potential function for the CH3 group, Kr=4.74+8.8×10−3 (J−125) mdyn/Å. The orbital contributions to Kr have been examined theoretically. Variation in fractional s character in the carbon orbital to hydrogen does not, of itself, lead to a significant variation in Kr. The force constant increases with increasing ionic character in the C–H bond, rather than as a result of hybridization changes.Keywords
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