1,2-Difluoroethane: the angular dependance on ~1 J_(CF) coupling constants is independent of hyperconjugation

摘要

1,2-Difluoroethane is widely recognised to adopt a lower energy gauche rather than anti conformation; this gauche effect has its origin in hyperconjugation; however, surprisingly the ~1 J_(Cf) coupling constant is not influenced by hyperconjugation; instead, its magnitude changes with the overall molecular dipole.