Knowledge Bank

Infrared and Raman spectra have been recorded for trans-$CFHCFHO18$ and trans-CFDCFDO. From good band shapes in the gas-phase infrared spectra, Raman depolarization ratios, and close parallels with the spectra of trans-CFHCFHCH$\mathrm{<mrow\; data-mjx-texclass="ORD">2</mrow>}$ and CFDCFDCH$\mathrm{<mrow\; data-mjx-texclass="ORD">2</mrow>}$ other than for the $CH2$-rich modes, we have secured a virtually complete assignment of the vibrational fundamentals of the ethylene oxides. This work marks the first observation of the effect on vibrational spectra of heavy atom substitution on a three-atom ring system. Only a limited-range survey of the infrared spectrum of the normal isotopic species of trans-difluoroethylene oxide is available. However, frequency shifts (or non-shifts) due to 0-18 substitution imply that $\nu \mathrm{<mrow\; data-mjx-texclass="ORD">2</mrow>}$(a) at $1480cm-1$ is largely CC (and CF) stretching, whereas $\nu 6$(a) at $950cm-1$ contains appreciable COC stretching and $V7$(a) at about $520cm-1$ contains appreciable COC bending.