Role of titanium oxidation states in polymerization activity of Ziegler-Natta catalyst: a density functional study

Bhaduri, Sumit ; Mukhopadhyay, Sami ; Kulkarni, Sudhir A. (2006) Role of titanium oxidation states in polymerization activity of Ziegler-Natta catalyst: a density functional study Journal of Organometallic Chemistry, 691 (12). pp. 2810-2820. ISSN 0022-328X

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Official URL: http://linkinghub.elsevier.com/retrieve/pii/S00223...

Related URL: http://dx.doi.org/10.1016/j.jorganchem.2006.02.019

Abstract

The role of titanium oxidation states in olefin polymerization activity for Ziegler-Natta (ZN) catalyst has been investigated using density functional calculations at B3LYP/LANL2DZ as well as extended LANL2DZ basis that includes diffuse and polarization functions for C, H and Cl. Using the simple [TiCl2CH3]n (n = +1, 0, -1) model catalyst systems, we could rationalize some of the well-known experimental facts with varying Ti oxidation states (+4, +3, +2) in the real ZN systems. Firstly, irrespective of Ti oxidation states, the activation barriers (Eact) for ethylene and syn propylene insertion in Ti-CH3 bond are comparable in accordance with experimental and modeling studies. Secondly, it was observed that Ti(IV) catalyst has the lowest Eact which progressively increase in the order Ti(IV) < Ti(III) < Ti(II) high spin < Ti(II) low spin catalysts in line with experimental and several modeling results. The effect of solvation on olefin insertion barriers are seen more prominent in case of Ti(IV) systems compared to other oxidation states.

Item Type:Article
Source:Copyright of this article belongs to Elsevier Science.
Keywords:Density Functional; Ziegler-Natta Catalyst; Titanium Oxidation States; Activation Barriers; Olefin Polymerization Activity; Solvation
ID Code:1999
Deposited On:08 Oct 2010 09:35
Last Modified:08 Oct 2010 09:35

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