1,2-Difluoroethane: the angular dependance on 1JCF coupling constants is independent of hyperconjugation

Abstract

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 ¹J_CF coupling constant is not influenced by hyperconjugation; instead, its magnitude changes with the overall molecular dipole.