Knowledge Bank

1,3-Disilacyclopent-4-ene has been synthesized and its far-infrared, mid-infrared, and Raman spectra have been analyzed. From the far-infrared data of the molecule in the vapor phase, which shows a series of ten bands between 48 and 85 $cm-1$, the ring-puckering potential energy surface was determined to be $V(cm-1)=1.48\times 105x4+0.30\times 104x2$, where x is the ring-puckering coordinate in Angstroms. This shows the molecule to be planar but to be not nearly as rigid as silacyclopent-2-$ene.1$ Other features in the infrared, Raman, and nmr spectra confirm that the interaction between the silicon atoms and the carbon-carbon double bond, while present, are reduced relative to silacyclopent-2-ene.