Knowledge Bank

The infrared spectrum of $CF3-CF2Cl$ has been examined in the gaseous phase in the region of $2.5\mu$ to $200\mu$. Eleven of the eighteen fundamental frequencies are thought to be assigned correctly, including the torsional oscillation which was observed at approximately $68cm-1$. Primary interest lay in determining the barrier to internal rotation. Assuming the usual three-fold potential function and omitting the six-fold terms, the barrier is calculated to be approximately $1750cm-1$ (5kcal/mole). This value for the barrier is one of the highest ever reported and calculation of the position of the energy levels reveals that at least fifteen levels lie under the barrier. Furthermore, the splitting between the A and E levels is calculated to be less than $0.05cm-1$ for these levels. $\mathrm{<mrow\; data-mjx-texclass="ORD">\ast </mrow>}$ This research was sponsored by The Robert A. Welch Foundation, Houston, Texas.