Assignment of the B 1 (Antisymmetric) Ring Deformation in Ethylene Oxide Using High-Resolution FT-IR

Assignment of the B1 (antisymmetric) ring deformation in ethylene oxide has been the subject of controversy. This B1 vibration should produce a type-A IR band, and Lord and Nolin report a Q-branch peak at 892 cm-1 which they assign as the B1 ring deformation. Thompson and Cave have suggested that the absorption maximum near 840 cm-1 results from this B1 fundamental. Lord and Nolin obtained a vapor-phase IR spectrum of ethylene oxide-d4, and they assigned the 809 cm-1 type-A band to the B1 ring deformation. By application of the product rule for the B1 class in ethylene oxide and ethylene oxide-d4, Lord and Nolin have demonstrated that it is reasonably certain that the B1 antisymmetric ring deformation must occur near 890 cm-1.