Fluorine Magnetic Resonance Studies. VII Fluorine-Fluorine Coupling Over Five Bonds in l-Fluoro-2-(2′-fluorophenyl)ethanes
DA Burgess, MF Finn, D Jordan, ID Rae, BD Walters
Australian Journal of Chemistry | Published : 1984
Spin-spin coupling between an aromatic fluorine and fluorines in an adjacent side chain (Ar-C-C-F), with J values in the range 2-5 Hz, is reported for four new compounds. The coupling probably arises from through-space interactions taking place when rotation of the side chain brings the two types of fluorine into close proximity. In a Diels-Alder adduct of fluoranil and 1-fluoro-4-methyl- anthracene, this proximity is denied the fluorines and no coupling is observed.