The vibrational selection rules and torsional barrier of methylsilylacetylene

Abstract

The molecular symmetry group of methylsilylacetylene is determined and used to classify the rotational-torsional wavefunctions and normal vibrations of the molecule. The vibrational selection rules are also derived and it is shown how a high resolution analysis of some of the perpendicular fundamental bands in the infra-red spectrum might yield the height of the torsional barrier. The experimental results are shown to be consistent with there being a near zero torsional barrier.