Pt L2,3 - Edge X-ray absorption spectroscopy investigation of zerovalent [Pt(PPh3)2(η2-L)] {L = C2H4, C60 and C2(CN)4} compounds

Journal of the Brazilian Chemical Society

Gilson H. M. Dias²  Nazareth F. Da Fonseca¹  Marcelo H. Herbst¹ 

[1] ,Universidade Estadual de Campinas Instituto de Química Campinas SP ,Brazil

关键词: Pt L2;    3-edge XAS;    zerovalent platinum compounds;    π back-donation energy;    spectral decomposition;   

DOI  :  10.1590/S0103-50532012000100006

来源: SciELO

【 摘 要 】

X-ray absorption spectra at the Pt L2,3-edges have been measured for three [Pt(PPh3)2(η2-L)] {L = C2H4, C60 and C2(CN)4} compounds. The spectral features are effective for measuring the π*-acid strength of ligands (L) coordinated to the Pt(PPh3)2 fragment. The energies of the dπ-orbitals are quantitatively determined using the difference between the edge jumping and the edge maximum shifts of the L2,3-white lines in the second derivatives of the spectra. The dπ-orbital energies follow the order [Pt(PPh3)2(η2-C2H4)] < [Pt(PPh3)2(η2-C60)] < [Pt(PPh3)2{η2-C2(CN)4}]. These dπ-orbital energies are in good agreement with the changes in the bound olefinic carbon bond lengths and the 31P NMR chemical shifts of the coordinated phosphines. Furthermore, the experimental values are in good agreement with available dπ-orbital interaction energy terms calculated using density functional theory for model [Pt(PH3)2(η2-L)] compounds.

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