Knowledge Bank

Raman spectra of the gaseous, liquid and crystalline states of $HCOOCH3$, $DCOOCH3$, and $HCOOCD3$ have been recorded. The vibrational data for methyl formate are consistent with a cis-planar skeletal structure and there is no evidence for a second conformation. An assignment of the 1 $\leftarrow$ 0 transition for the methyl torsional mode is presented for each isotope with the magnitude of the torsional barrier determined to be approximately 1.1 kcal/mole. A $V\ast$ value of 82.1 kcal/mole is calculated for the $C-O$ torsion by using the observed, depolarized Raman line at 338 $cm-1$ and microwave structural parameters. The magnitude and nature of the C-O torsional barrier will be discussed.