Gauche preference in 1,2-difluoroethane originates from both orbital and electrostatic stabilization interactions

The origin of the gauche preference in 1,2-difluoroethane has been investigated by using an energy decomposition analysis (EDA). The EDA results show that favourable orbital interactions are not the sole source of stabilization in this conformer. Electrostatic interactions, too, are more attractive in the gauche than in the anti form. This finding opposes our traditional view of electrostatic interactions and their influence on conformational equilibria, but points out that they should be considered as an all-charge phenomenon, rather than partial interaction between pairs of bonds.