The band associated with the N-H stretching vibration for the simple amines is usually well defined at a single frequency. However, the bands for the alkyl ammonium salts are quite complex, and the numbers, intensities, and positions of these bands are determined by the interactions of the protons associated with the ?NH+2 group with the anion. Large interactions lead to considerable lowering in the N-H stretching frequencies. For the alkylammonium sulphates this interaction also affects the number of frequencies observed for the sulphate group. When the alkylammonium sulphate is complexed to iron(III), in a complex of the stoicheiometric formula (R2NH2)2FeOH(SO4)2, the infrared spectrum is consistent with much weaker interaction between the alkylammonium protons and the anion.