Molecular Geometry of<i>cis</i>- and<i>trans</i>-Polyacetylene by Nutation NMR Spectroscopy

Abstract

The carbon-carbon bond lengths in polyacetylene have been directly measured with use of nutation NMR spectroscopy. 1.36 and 1.44 \AA{} were found for the double and single bonds, respectively, in trans-${(\mathrm{CH})}_{x}$, and 1.37 \AA{} was found for the double bond in the cis isomer. Over the temperature range 4.2-300 K, the dynamical single-double bond interchange predicted for chains in trans-${(\mathrm{CH})}_{x}$ containing a mobile soliton defect was not observed.