The Raman spectra of crystal powders

Summary

The paper reports the Raman spectra of crystalline NH₂OH·HCl, (NH₂OH)₂·H₂SO₄; N₂H₄·2HCl, and N₂H₄·H₂SO₄, photographed by the powder technique recently described by the author. The spectra of the chlorides reveal many interesting features relating to the vibrations of the hydroxylammonium and hydrazinium ions, the most characteristic of which is perhaps the multiplicity and diffuseness of the N−H bands whose frequencies range roughly from 2500 to 3200 wave numbers. The N−H bands are considerably weakened and are very much more diffuse in the case of the sulphates. There is a probable structural similarity between the [H₃N.OH]⁺ ion and H₃C·OH and [H₃N·NH₃]⁺⁺ and H₃C·CH₃ although the spectra of the ions are very much more complicated than those of the corresponding organic molecules. From a comparison of the Raman spectra of tri- and pentavalent nitrogen derivarives, it is found that there is a definite lowering of the N−H frequencies in the compounds of the latter class. It is therefore concluded that when the covalency of nitrogen changes from three to four, there is a definite weakening of the N−H bond.