Knowledge Bank

The spectrum of methylammonium chloride was examined by $Waldron1$. We have measured the spectra of the four methylammonium halides at $21\circ C$, $-190\circ C$ and at intermediate temperatures in the solid phase. The room temperature spectra are consistent with $C3v$ symmetry. With the probable exception of the fluoride, the salts undergo phase changes at low temperatures and the symmetry is lowered. These compounds exhibit hydrogen bonding of the $N+-H-X-$ type (X = F, Cl, Br, I) with some regular changes from one halogen to the other. The spectra are discussed in detail.