The Vibration Spectra and Structure of the Cyanogen Halides

Abstract

The Raman spectra of the cyanogen halides in the liquid state or in alcoholic solution contain 3 frequencies v1, v2, and v3. In the order chloride, bromide, iodide, v1 = 2201, 2187, 2158 cm—1; v2 = 729, 580, 470; v3 = 397, 368, 321; the order of intensities of Raman transitions is v1>v2>v3. The relative values of the frequencies indicate a linear arrangement of the nuclei in the lowest electronic state of these molecules, and the data are in accord with the structure X–C≡N rather than X–N=C.