ChemInform Abstract: A Two‐Tunneling Path Internal‐Axis‐Method‐Like Treatment of the Microwave Spectrum of Divinyl Ether.

Abstract

Abstract The microwave spectrum of the cis-trans conformer of divinyl ether, previously measured by Hirose and co-workers, has been fitted using a two-dimensional internal-axis-method (IAM) like treatment which accounts for the 27-MHz tunneling splitting displayed by this molecule. This two-dimensional IAM-like treatment begins by first determining the various feasible tunneling path(s) connecting the two frameworks of the molecule. For the tunneling process corresponding to an antigeared rotation of each vinyl unit about axes coinciding with the respective CO bonds, two limiting cases are considered: if the molecule goes through a planar configuration during the tunneling, only one tunneling path arises; if the intermediate configuration is not planar, two equivalent tunneling paths occur. The consequences for the J and K dependence of the splitting are examined, and using this formalism the microwave data are fitted with a root-mean-square deviation of 0.156 MHz. The parameters related to the J and K dependence of the splitting are also determined and their values are interpreted in favor of a two-tunneling path system. A comparison with the values obtained theoretically for those parameters is also carried out.