KONSTANTINA VASILATOU, JULIE M. MICHAUD, DENITSA BAYKUSHEVA, GUIDO GRASSI AND FREDERIC MERKT, Laboratorium für Physikalische Chemie, ETH Zürich, CH-8093 Zürich, Switzerland.
High-resolution photoelectron spectra of cyclopropene (c-C3H4) and several of its deuterated isotopomers have been recorded. From the analysis of the almost fully resolved rotational structure of the origin of the X+ 2B2 X 1A1 ionizing transition of c-C3H4, c-C3H3D, c-C3H2D2, c-C3HD3 and c-C3D4 and the observation of several low-lying vibrational levels of the corresponding cations, we conclude that the cyclopropene cation has an equilibrium structure deviating from C 2v symmetry. We believe that the cation is subject to a large-amplitude tunnelling motion along a mode of a2 symmetry involving a twist of the CH2 group and an asymmetric out-of-plane bending of the CH units. The reasons for this belief and also currently unresolved aspects of our analysis will be discussed.
%\beginlist[\arabicRefcounter]\hfill\usecounterRefcounter \topsep=0mm \partopsep=2mm emsep=0mm \parsep=0mm \labelwidth=5mm \labelsep=2mm \leftmargin=7mm
% em\labelref2 A. B. Burrill and P. M. Johnson, \textslJ. Chem. Phys. \textbf2001, \textsl115, 133.