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The Nature of the Active Site in Ziegler–Natta Olefin Polymerization Catalysis Systems – A Computational Investigation
Author(s) -
Kumawat Jugal,
Kumar Gupta Virendra,
Vanka Kumar
Publication year - 2014
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.201402180
Subject(s) - chemistry , active center , polymerization , active site , catalysis , natta , polymer , olefin fiber , polymer chemistry , olefin polymerization , ziegler–natta catalyst , coordination polymerization , solution polymerization , organic chemistry
Full quantum chemical calculations with density functional theory (DFT) show that a principal role of donors in Ziegler–Natta (ZN) olefin polymerization catalysts is to coordinate to the metal center at the active sites on the MgCl 2 surface. Thereby, the behavior of the catalyst is modulated to favor insertion over termination and, thus, polymerization occurs. This is shown to be true for a range of different donors. The calculations indicate that active sites that feature anionic chloride ligands at the titanium center (the conventional model for the active site) would lead to lower‐molecular‐weight polymers. If an –OC 2 H 5 group were present instead of a chloride ligand, the active site would much more effectively produce long chain polymers. Therefore, the current work provides important new insights into the nature of the ZN polymerization process.