| 摘 要： | An ab initio molecular orbital study was performed to determine the effects of anions and cations on the π-complexation of C2H4 on MX(M=Ag, Cu; X=F, Cl). The calculated results show the following order of adsorption strength: F-＞Cl- for anions; Cu ＞Ag for cations. The results can be explained by the detailed analysis of atomic charge, orbital energy and orbital population by using the natural bond orbital(NBO) theory: (1) anions with stronger electronegativity can attract more electrons from the s orbital of M, while at the same time it does not obviously weaken the d orbital occupation of M, thus the nearly vacant s orbital and the sufficiently filled d orbitals of M help with forming σ-donation and d-π* backdonation with the π orbital and the π* orbital of olefin, respectively; (2) a smaller energy gap of symmetry-adapted orbitals between olefin and a cation can favor the electron transfer, that is why Cu forms stronger adsorption with olefin than Ag does.
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