A density functional study of [M(PH3)(2)(eta(2)-C2X4)] alkene complexes for the Group 10 metals Ni, Pd, Pt: the effect of electron-attracting substituents

Density functional calculations have been performed for [M(PH3)(2)(C2X4)] c omplexes with M = Ni, Pd or Pt and X = H, F or CN to study the effect of el ectron-attracting substituents on the metal-olefin bonding. The optimised g eometries have been found to be in good agreement with experimental crystal structure data. The electronic structure has been analysed in terms of the Chatt-Dewar-Duncanson model and the contribution from pi back donation was found to dominate over that from sigma donation for both ethylene and subs tituted ethylene complexes. Reliable values have been calculated for the me tal-olefin bond dissociation energies and compared with the available exper imental data.