Molecular Geometry ofcis- andtrans-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 Å were found for the double and single bonds, respectively, in trans-${\left(\mathrm{CH}\right)}_x$, and 1.37 Å 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-${\left(\mathrm{CH}\right)}_x$ containing a mobile soliton defect was not observed.