VIBRATIONAL AND ROTATIONAL SPECTRA AND AB-INITIO CALCULATIONS OF THIOCYANATOETHENE

Raman spectra of thiocyanatoethene (TCE) as a liquid at various temper atures and of the amorphous and crystalline solids at liquid nitrogen temperature were recorded. IR spectra in the 4000-400 cm(-1) region of the vapour, liquid, amorphous and crystalline solids at low temperatu re, and of the compound isolated in argon and nitrogen matrices at 5 K with the hot nozzle technique were obtained. Microwave spectra of TCE were recorded in the 10-39 GHz region employing Stark modulation. Are as of special interest were also investigated by use of the RFMWDR dou ble resonance technique. Ab initio calculations with different basis s ets were carried out. The compound exists as a mixture of syn and gauc he conformers in the vapour and liquid states, while the more stable s yn was present in the crystal. An enthalpy difference of 5.7(10) kJ mo l(-1) and a barrier of 8.4(3) kJ mol(-1) was found.