MINDO (Modified Intermediate Neglect of Differential Overlap) 3 Study of the Ethylene Dication

摘要

Mass spectral evidence was recently presented for the formation of the dication derived from ethylene. Since this seems to be the smallest organic dication whose existence has been unequivocally demonstrated, its structure and other properties are of theoretical interest. The original report included the results of an ab initio calculation for the dication which, however, was carried out assuming its geometry to be the same as that of ethylene. Since the geometry was not optimized, this amounted to a calculation of the vertical double ionization of ethylene and did not address either the structure or the properties of the ground state dication itself. This gap has been filled by a recent ab initio investigation by Lammertsma et al. in which the C2H4(++) potential surface was explored in some detail. Five stationary points were located, of which, however, only one proved to be a definite minimum, this having a D sub 2d structure in which the methylene groups are planar but orthogonal to one another. MINDO/3 calculations are reported for the dication, C2H4(++), derived from ethylene. Four minima, corresponding to species of similar energies, were located on the corresponding potential surface.