Bonding of ethylene to diatomic nickel according to a self-consistent-field, xα, scattered-wave model

The electronic structure of a model "surface complex" consisting of a Ni diatom and an ethylene molecule has been calculated using the self-consistent-field, Xα, scattered-wave method. Comparison of calculated π-orbital bonding shifts with recent photoemission spectra for chemisorption of ethylene on nickel favors a π-bonded complex over a di-σ-adsorbed complex. Charge distributions of various molecular orbitals indicate that the C-C double bond is weakened more for the latter molecular arrangement, suggesting such a complex as a likely intermediate in heterogeneous reactions.