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Structural and electronic effects in metallocene catalysts studied by x‐ray techniques
Author(s) -
Silveira Fernando,
de Sá Denise Santos,
da Rocha Zênis Novais,
do Carmo Martins Alves Maria,
dos Santos João Henrique Zimnoch
Publication year - 2008
Publication title -
x‐ray spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.447
H-Index - 45
eISSN - 1097-4539
pISSN - 0049-8246
DOI - 10.1002/xrs.1106
Subject(s) - methylaluminoxane , metallocene , chemistry , catalysis , polymer chemistry , polymerization , organometallic chemistry , x ray photoelectron spectroscopy , ethylene , gel permeation chromatography , inorganic chemistry , polymer , organic chemistry , nuclear magnetic resonance , physics
A series of metallocenes, namely, [Cp 2 ZrCl 2 ], [(MeCp) 2 ZrCl 2 ], [( n BuCp) 2 ZrCl 2 ], [( i BuCp) 2 ZrCl 2 ], [( t BuCp) 2 ZrCl 2 ], [Et(Ind) 2 ZrCl 2 ], [Et(IndH 4 ) 2 ZrCl 2 ], and [MeSi 2 (Ind) 2 ZrCl 2 )] 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.