Infrared and raman study of ν4 and ν5 motions of light and deuterated nitromethane evidence of conformational equilibria

Infrared and Raman spectroscopy has been used to study totally symmetric ν4 and ν5 motions of CH3NO2 and CD3NO2 isotopomers, in order to ascertain the nature of the low-frequency features appearing in these bands. A study, under high-resolution conditions, of the gaseous phase infrared spectra and of the temperature effects, carried out on both liquid and gaseous molecules, has allowed us to proove that these features are connected to the effects of conformational population and not to hot band transitions, as it has been previously reported.