The rotational and vibrational spectra,structure and dipole moment of 1,3-dioxole-2-thione

Rotational and centrifugal distortion constants are determined for the ground state and several excited states of the lowest vibrational mode of l,3-dioxole-2-thione, the “envelope” ring-bending mode. The structure of the molecule is planar. The A-constant is 1% larger than that of 1,3-dioxole-2-one (vinylene carbonate), which indicates small changes in ring-geometry on substituting CS for CO. The dipole moment of 1,3-dioxole-2-thione deduced from Stark-effect measurements is (1.60 ± 0.02) × 10^?29 Cm (4.81 ± 0.06 D). IR and Raman spectra lead to a complete analysis of the normal modes of vibration, based partially on a normal coordinate calculation.