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Activity of phenoxy-imine titanium catalysts in ethylene polymerization : A quantum chemical approach

Nikitin, Sergey V.; Nikitin, Viktor V. LU ; Oleynik, Ivan I.; Oleynik, Irina V. and Bagryanskaya, Elena G. (2016) In Journal of Molecular Catalysis A: Chemical 423. p.285-292
Abstract

The mechanism of ethylene polymerization on phenoxy-imine (FI) titanium catalysts was studied theoretically to identify the major factors affecting the catalytic activity. Geometry optimizations of FI ligands, octahedral titanium dichloride complexes, active cationic species, and their π‐complexes with ethylene as well as calculations of the energy profile of chain propagation were performed at the BP86-D3 level. We found that the calculated energy gaps between frontier orbitals (HOMO and LUMO) in the active cations of the catalysts correlate with the experimental activity values. High activities of FI catalysts with α‐Cumyl groups were attributed to smaller HOMO-LUMO gaps due to hyperconjugation between π-systems of α‐Cumyl and... (More)

The mechanism of ethylene polymerization on phenoxy-imine (FI) titanium catalysts was studied theoretically to identify the major factors affecting the catalytic activity. Geometry optimizations of FI ligands, octahedral titanium dichloride complexes, active cationic species, and their π‐complexes with ethylene as well as calculations of the energy profile of chain propagation were performed at the BP86-D3 level. We found that the calculated energy gaps between frontier orbitals (HOMO and LUMO) in the active cations of the catalysts correlate with the experimental activity values. High activities of FI catalysts with α‐Cumyl groups were attributed to smaller HOMO-LUMO gaps due to hyperconjugation between π-systems of α‐Cumyl and (N‐aryl)salicylaldimine moieties in the active cations. The correlation provides a qualitative estimate of the catalytic activity for further design of new FI titanium complexes.

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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Catalytic activity, DFT, Ethylene polymerization, FI catalyst, Phenoxy-imine
in
Journal of Molecular Catalysis A: Chemical
volume
423
pages
8 pages
publisher
Elsevier
external identifiers
  • Scopus:84978419529
ISSN
1381-1169
DOI
10.1016/j.molcata.2016.07.010
language
English
LU publication?
yes
id
5d948bfa-ee0b-4398-a5f3-6f0eee47452a
date added to LUP
2016-10-13 11:25:07
date last changed
2016-10-13 11:25:07
@misc{5d948bfa-ee0b-4398-a5f3-6f0eee47452a,
  abstract     = {<p>The mechanism of ethylene polymerization on phenoxy-imine (FI) titanium catalysts was studied theoretically to identify the major factors affecting the catalytic activity. Geometry optimizations of FI ligands, octahedral titanium dichloride complexes, active cationic species, and their π‐complexes with ethylene as well as calculations of the energy profile of chain propagation were performed at the BP86-D3 level. We found that the calculated energy gaps between frontier orbitals (HOMO and LUMO) in the active cations of the catalysts correlate with the experimental activity values. High activities of FI catalysts with α‐Cumyl groups were attributed to smaller HOMO-LUMO gaps due to hyperconjugation between π-systems of α‐Cumyl and (N‐aryl)salicylaldimine moieties in the active cations. The correlation provides a qualitative estimate of the catalytic activity for further design of new FI titanium complexes.</p>},
  author       = {Nikitin, Sergey V. and Nikitin, Viktor V. and Oleynik, Ivan I. and Oleynik, Irina V. and Bagryanskaya, Elena G.},
  issn         = {1381-1169},
  keyword      = {Catalytic activity,DFT,Ethylene polymerization,FI catalyst,Phenoxy-imine},
  language     = {eng},
  month        = {11},
  pages        = {285--292},
  publisher    = {ARRAY(0x9d5e1d0)},
  series       = {Journal of Molecular Catalysis A: Chemical},
  title        = {Activity of phenoxy-imine titanium catalysts in ethylene polymerization : A quantum chemical approach},
  url          = {http://dx.doi.org/10.1016/j.molcata.2016.07.010},
  volume       = {423},
  year         = {2016},
}