The Infrared and Raman Spectra of Dicyanoacetylene

Abstract

The preparation of dicyanoacetylene, N≡C–C≡C–C≡N, is outlined and its infrared and Raman spectra are presented. An assignment is given for 8 of the 9 fundamental frequencies which explains the observed combination tones very satisfactorily. All features of the spectra are compatible with D_∞h symmetry, including particularly the infrared band contours, the lack of coincidences between infrared and Raman frequencies, and the operation of selection rules for the combination tones. Results of a normal coordinate treatment are included.