THEORETICAL STUDY OF CYCLOPROPENE AND ITS C3H4 ISOMERS

Ab initio SCF MO and CI calculations are reported for the three C3H4 isomers cyclopropene, methylacetylene and allene. The closed shell nature of each of these molecules allows for a good theoretical comparison of their stabilities and ionization potentials by the SCF method. It is pointed out that cyclopropene differs from most 22 electron systems with a triatomic skeleton in that it possesses a non-linear equilibrium structure; this fact is related to its unusual ground state electronic configuration, which corresponds to a highly excited state in simple triatomics such as CO2 and N3-. The electronic spectrum and the methylene rotational barrier of cyclopropene are also investigated. © 1969 Springer-Verlag.