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A 13 C{ 1 H} double resonance study of the signs of 1 H 19 F and 13 C 19 F spin coupling constants in fluorobenzenes and 2‐fluoropyridine
Author(s) -
Brey W. S.,
Jaques L. W.,
Jakobsen H. J.
Publication year - 1979
Publication title -
organic magnetic resonance
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0030-4921
DOI - 10.1002/mrc.1270120415
Subject(s) - fluorobenzene , resonance (particle physics) , coupling constant , physics , chemistry , analytical chemistry (journal) , atomic physics , organic chemistry , benzene , particle physics , chromatography
The signs of all 13 C 19 F and 1 H– 19 F coupling constants in fluorobenzene, some substituted derivatives, and in 2‐fluoropyridine have been related using single‐frequency 13 C{ 1 H} double resonance techniques. All 13 C 19 F couplings in these compounds are shown to be positive. Direct experimental proof is given for a positive sign for the small five‐bond 1 H 19 F coupling constant (=0.2—0.3 Hz) in fluorobenzene. The positive sign for 4 J (C‐4, F) in fluorobenzene is in accord with a positive π‐electron contribution to this coupling.