Structural and electronic effects in metallocene catalysts studied by x‐ray techniques |
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| Authors: | Fernando Silveira Denise Santos de Sá Zênis Novais da Rocha Maria do Carmo Martins Alves João Henrique Zimnoch dos Santos |
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| Affiliation: | 1. Instituto de Química, UFRGS, Av. Bento Gon?alves, 9500–Porto Alegre ‐ 91509‐900, Brazil;2. Instituto de Química, UFBA, Campus de Ondina ‐ Salvador ‐ 40170‐290, Brazil |
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| Abstract: | A series of metallocenes, namely, [Cp2ZrCl2], [(MeCp)2ZrCl2], [(nBuCp)2ZrCl2], [(iBuCp)2ZrCl2], [(tBuCp)2ZrCl2], [Et(Ind)2ZrCl2], [Et(IndH4)2ZrCl2], and [MeSi2(Ind)2ZrCl2)] were analyzed by extended x‐ray absorption fine structure (EXAFS) and x‐ray photoelectron spectroscopy (XPS). Complementary techniques, UV–vis spectroscopy and cyclic and differential pulse voltammetry, were employed to characterize the organometallic complexes. The catalysts were evaluated in ethylene polymerization, having methylaluminoxane (MAO) as the cocatalyst, and the resulting polymers were characterized by gel permeation chromatography. The structural and electronic effects caused by the coordination sphere around the metal center and their effects on the catalytic activity and polymer characteristics are discussed. Copyright © 2008 John Wiley & Sons, Ltd. |
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