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Exceptionally large 13C–13C coupling constants of compounds containing a CF3 group

✍ Scribed by Willy Gombler

Publisher
John Wiley and Sons
Year
1990
Tongue
English
Weight
402 KB
Volume
28
Category
Article
ISSN
0749-1581

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✦ Synopsis

Abstract

Coupling constants, ^1^J(^13^C,^13^C), of compounds containing a CF~3~ group are reported. The values for the coupling of the CF~3~ carbon with the neighbouring carbon are exceptionally large. In a series of compounds in which the CF~3~ group is bonded to an sp^3^, sp^2^ or sp carbon the ^1^J(C,C) values show a good linear correlation with the product of the s characters of the two orbitals forming the CC bond. Furthermore, compounds containing a CCl~3~ group have been measured. A correlation of the ^1^J(CC) values with the sum of the group electronegativities in compounds of the CX~3~‐CY~3~ type is found. The results for compounds containing highly electronegative substituents suggest a contribution to the CC coupling from a relatively large variation of the valence‐shell s‐orbital density at the carbon nucleus, S~c~^2^(0). Additional ^13^C and ^19^F NMR data of the compounds are presented.

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