Vibration Spectra and Rotational Isomerism of Chain Molecules. III. Ethyl Methyl Sulfide and Deuterium Compounds

Abstract

The Raman spectra of ethyl methyl sulfide and its three deuterated compounds CD3SC2H5, CH3SCH2CD3, and CH3SC2D5 were measured for the liquid and crystalline states. The Raman spectra of the undeuterated species in the gaseous state were measured at different temperatures. The normal vibration frequencies were calculated by using a consistent set of force constants for aliphatic sulfides. The combination of the spectral observations of the deuterated compounds and the normal vibration calculations showed that only the gauche form exists in the crystalline state and the trans and gauche forms coexist in the liquid and gaseous states. The enthalpy difference between the gauche and trans forms in the gaseous state, ΔHG–T, was obtained as −30±50 cal/mol.