Knowledge Bank

The infrared spectra of gaseous $CH3NF2$ and $CD3NF2$ and of solid $CH3NF2$ have been recorded. They indicate an essentially free rotation of the methyl group about the C-N bond even at about $100\circ K$., and suggest a coplanar configuration of the bonds about nitrogen. Thus the structure of $CH3NF2$ seems more like that of $CH3NO2$ than that of $CH3NH2$. The assignments are discussed in terms of local $C2v$ symmetry in the $C-NF2$ subgroup and $C3v$ symmetry in the $N-CH3$ subgroup. The $A1$ motions of both subgroups will be coupled through the C-N stretching vibration which is common to both.