Acta Phys. -Chim. Sin. ›› 2012, Vol. 28 ›› Issue (04): 811-817.doi: 10.3866/PKU.WHXB201202082


Electronic Structures of Group IB Metal-Ethylene Complexes [N{(Me)C(Ph)N}2]M-C2H4 (M=Cu, Ag, Au)

QIU Yi-Xiang, WANG Shu-Guang   

  1. School of Chemistry and Chemical Technology, Shanghai Jiao Tong University, Shanghai 200240, P. R. China
  • Received:2011-11-14 Revised:2012-01-12 Published:2012-03-21
  • Contact: WANG Shu-Guang
  • Supported by:

    The project was supported by the National Natural Science Foundation of China (20973109).

Abstract: The geometries, electronic structures, and bonding energies of coinage metal-ethylene complexes LM-C2H4 (L=[N{(Me)C(Ph)N}2]; M=Cu, Ag, Au) were investigated by Hartree-Fock, Møller- Plesset perturbation (MP2), second-order approximate coupled-cluster (CC2), and density functional theory (DFT) methods. The MP2, CC2, and DFT methods performed well in reproducing the experimental geometric features of LM-C2H4. The bonding in LM-C2H4 can be described as a synergistic combination of σ-donor and π-acceptor interactions between the LM and C2H4 π-system. Both σ-donor and π-acceptor contributions increased the C=C bond length and decreased the C=C bond strength by removing electron density from the bonding π orbital and increasing electron density in the anti-bonding π* orbital, respectively. The results of natural population analysis and energy decomposition analysis show that the LM→C2H4 back-donation contribution to the LM-C2H4 bonding is higher than that of the C2H4→LM donation, but this order is reversed in the M+-C2H4 systems. Therefore, it is not appropriate to use M+-C2H4 as a computational model for electronic structures studies of LM-C2H4. The effects of changing the metal on the structural and electronic properties, such as C=C bond length, charge populations of C2H4, and LM-C2H4 interactions, were large. Compared with LCu and LAg, LAu had the strongest ability to accept and donate electrons. Consequently, it showed the maximum reduction in the π orbital electron density and increase in the π* orbital density. Therefore, activation of the C=C bond by LAu was more effective than by LCu and LAg. However, the effects of electron donating or withdrawing ability of the auxiliary ligands on the above properties were small.

Key words: Metal-ethylene complex, Ab initio, Density functional theory, Electronic structure, Energy decomposition analysis


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