Vibrational spectrum and normal coordinate analysis of CX₃CO₂NX₄(X=H or D)

The vibrational spectrum of ammonium acetate at room temperature and 77 K is reported. The observed factor group splitting between four acetate ions is slight in each internal mode. The normal coordinate analysis is carried out under the assumption of neglect of hydrogen atoms. Good agreement between observed and calculated frequencies is obtained for the lattice vibrations. It is clarified that the hydrogen bond has considerable strength and a very strong Raman band at 58 cm −1 in CH 3 CO 2 NH 4 is a libration of the acetate ion about an axis perpendicular to the molecular plane. The strong IR band at 260 cm −1 in CH 3 CO 2 NH 4 is discussed.