Raman spectra and vibrational potential function of polycrystalline azomethane and azomethane-d6

Raman spectra of polycrystalline azomethane $({\mathrm{CH}}_3\mathrm{N}={\mathrm{NCH}}_3)$ and azomethane‐d₆ were examined at liquid nitrogen temperatures using argon ion laser excitation. These data, in conjunction with a normal coordinate analysis, provide a basis for a modification of the vibrational assignments for the azomethane system. A 17 parameter molecular force field, based upon the solid state vibrational frequencies of azomethane and its deuterated analog, was determined by least‐squares procedures. The unusual coupling characteristics between the X–N stretching and X–N=N bending coordinates are discussed for both azomethane and trans‐1,2‐difluorodiazine, $\mathrm{FN=NF}$ .