Far-infrared spectrum and ab initio calculations for vinylene carbonate

Abstract

The far-infrared spectrum of vinylene carbonate shows five closely spaced bands near 233cm−1, characteristic of a nearly harmonic ring-puckering potential energy function. Using a coordinate dependent kinetic energy expansion, the potential energy function was determined to be V(cm−1)=1.652×105x2−1.416×105x4 where x is the puckering coordinate in Å. This shows the molecule to be much more rigid than the similar 3-cyclopenten-1-one due to π bonding interactions involving the oxygen atoms adjacent to the carbonyl group. Ab initio calculations with a B3LYP/6-311++G∗∗ basis set yield structural data in good agreement with the previous microwave work and also predict vibrational frequencies that correspond closely to the experimental values.