MICROWAVE SPECTRUM AND RING-BENDING VIBRATION OF 3-OXETANONE

Author Institution: Department of Chemistry, University of CaliforniaThe microwave spectrum of 3-oxetanone, \begin{eqnarray*}\begin{array}{c}{O}-{CH}_{2}-{C}=O\\-{CH}_{2}-\end{array}\end{eqnarray*}, has been observed and assigned in the ground vibrational state and first five excited states of the ring-bending vibrational mode. The spectra of both $C^{13}$ isotopically substituted species in natural abundance have also been measured. The features of the microwave spectrum were consistent with a single-minimum ring-bending potential function as determined in a previous far-infrared study. The observed variation of the rotational constants was fit to the vibrational states of this potential. A model for the variation was set up assuming curvilinear motion of the atoms with no bond stretching that reproduces the observed variation of the rotational constants in a reasonable manner. The vibrational potential was interpreted in terms of the energy contributions from ring-angle deformations and torsional interactions. The $C^{13}$ data were used to determine a partial structure of the molecule which gave: {r}({C-C})=1.521\AA<({C-C-C})=88.13^{\circ} The dipole moment for the ground vibrational state was measured as $\mu$ = 0.887D