Infrared Spectrum of Cyanogen Azide

The infrared spectrum of cyanogen azide (N3CN) has been recorded in the gas phase between 3000 and 70 cm−1. The nine vibrational fundamentals have been located. Assignments of the seven in-plane and two out-of-plane fundamentals have been made on the basis of observed and calculated vibration–rotation band contours. Two strong Fermi doublets have been observed in the triple bond stretching region of the spectrum. Valence force constants have been calculated for the in-plane vibrations of cyanogen azide, and the distribution of potential energy among the force constants obtained, in order to give qualitative descriptions of the normal modes. Thermodynamic quantities of cyanogen azide have been calculated for several temperatures and compared with corresponding quantities for methyl azide.