Far-infrared spectra and pseudorotational potential energy function of 1,3-oxathiolane-2,2-d2

Abstract

THe far-infrared spectra of 1,3-oxathiolane-2,2-d{sub 2} showing pseudorotational single and double quantum jump transitions, radial transitions, and pseudorotational-radical difference bands have been recorded and analyzed. Fourteen pseudorotational (ring bending) transition frequencies were observed in the 30-110-cm{sup {minus}1} region and were fit with the one-dimensional potential function 2V (cm{sup {minus}1})={minus}577(1 - cos 2{Phi}) + 104(1 - cos 4{Phi}). The molecule is twisted with a barrier to pseudorotation of 577 {plus_minus} 20 cm{sup {minus}1} (1.65 {plus_minus} 0.06 kcal/mol). The barrier height agrees well with the 541 {plus_minus} 20 cm{sup {minus}1} value determined for the undeuterated species. As was the case for the parent molecule, the spectra recorded include transition frequencies occurring above the barrier. In addition, several radial transitions arising from different pseudorotational states of 1,3-oxathiolane-2,2-d{sub 2} have been observed in the 280-310-cm{sup {minus}1} region. Those in the pseudorotational ground state can be fit with a one-dimensional double-minimum function with a barrier to planarity of 3000 cm{sup {minus}1}. However, this value from the one-dimensional approximation is believed to be too high. Difference bands in the 170-230-cm{sup {minus}1} region and double quantum transitions in the 140-200-cm{sup {minus}1} region were also detected and used to confirm the assignments. 15 refs., 5 figs., 5 tabs.