Molecular Structure and Vibrational Spectra of Ethyl Cyanide

Abstract

The infrared spectra for the gaseous and liquid states, and the Raman spectra for the liquid state, including intensity and polarization data, are reported for ethyl cyanide (C2H5CN). A normal coordinate treatment has been made for four planar and five nonplanar skeletal vibrational modes. The observed spectra are in accord with a C8 model for this molecule. A complete assignment of frequencies to the fundamental modes of vibration is made for ethyl cyanide. From the spectroscopic data, the height of the barrier hindering internal rotation is estimated to be 5200 cal. The thermodynamic functions for ethyl cyanide have been calculated to 1000°K.