@article { ISI:000343819200016,
	title = {Nature of the active site in ziegler-natta olefin polymerization catalysis systems - a computational investigation},
	journal = {European Journal of Inorganic Chemistry},
	number = {29},
	year = {2014},
	month = {OCT},
	pages = {5063-5076},
	publisher = {WILEY-V C H VERLAG GMBH},
	address = {BOSCHSTRASSE 12, D-69469 WEINHEIM, GERMANY},
	abstract = {<p>Pull quantum chemical calculations with density functional theory (DET) show that a principal role of donors in Ziegler-Nana (ZN) oh-din polymerization catalysts is to coordinate to the metal center at the active sites on the MgCl2 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 riolymers. If an -OC2H5 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.</p>},
	keywords = {Alkene polymerization, Density functional calculations, heterogeneous catalysis, Insertion, Polymers},
	issn = {1434-1948},
	doi = {10.1002/ejic.201402180},
	author = {Kumawat, Jugal and Gupta, Virendra Kumar and Vanka, Kumar}
}
@article { ISI:000379531300011,
	title = {Effect of donors on the activation mechanism in ziegler-natta catalysis: a computational study},
	journal = {Chemcatchem},
	volume = {8},
	number = {10},
	year = {2016},
	month = {MAY},
	pages = {1809-1818},
	publisher = {WILEY-V C H VERLAG GMBH},
	address = {POSTFACH 101161, 69451 WEINHEIM, GERMANY},
	abstract = {<p>Full quantum chemical calculations, using density functional theory (DFT), have been conducted to explain the effect of donors on the {\textquoteleft}{\textquoteleft}activation mechanism{\textquoteright}{\textquoteright} in the Ziegler-Natta (Z-N) catalyst system. In the activation mechanism, the inactive (TiCl4)-Cl-IV catalyst converts into the active (TiCl2Et)-Cl-III catalyst with the help of the AlEt3 present in the system. The donors that have been considered in this study are: ethyl benzoate (eb), two representative diether cases, a phthalate donor, and a silyl ester donor. The results indicate that eb and the diether donor cases donor have a negative effect on the barriers for the activation mechanism. However, the eb donor can be displaced from the MgCl2 surface by AlEt3, which matches experimental observations. For the phthalate, silyl ester and TiCl3-OC4H8Cl cases, the results indicate that a significant induction period would be present in Z-N systems employing such donors or having such a catalytic center, before catalysis could commence.</p>},
	keywords = {Alkylation, aluminum, Density functional calculations, surface chemistry, titanium},
	issn = {1867-3880},
	doi = {10.1002/cctc.201600281},
	author = {Kumawat, Jugal and Gupta, Virendra Kumar and Vanka, Kumar}
}
