A reassignment of the fundamentals of ethylene oxide-d4 has been made on the basis of a new study of its infrared spectrum as a gas and as a solid at -196°C. Spectra are also reported for C2H3DO, C2D3HO, C2D2H2O (gem, cis and trans isomers), and C2H418O. The new data for C2D4O have been combined with a revised assignment for ethylene oxide-h4 to derive a force field which reproduces all the frequencies for these molecules with an average error of less than 0·5% for the A1, and B1 blocks and less than 1·0% for the A2 and B2 blocks. As noted by earlier workers there is better agreement in the latter blocks if rocking modes are assumed to have higher frequencies than twisting modes, although the possibility of a situation with extensive mixing cannot be overlooked. The force field has been used to calculate the fundamentals of all the other ethylene oxides. Agreement was reasonable for most, but rather poor for the trans d2 molecule where the failure to calculate a fundamental with frequency near that of an observed gas phase absorption band of B-type contour at 754 cm-1 was a particular shortcoming. The possibility of improving the force field by incorporation of other data into the calculations is briefly discussed.
|Number of pages||15|
|Journal||Spectrochimica Acta Part A: Molecular Spectroscopy|
|Publication status||Published - 1975|