Theoretical study of the propagation barrier of ethylene polymerization with TiR2 (R=OCH3 or CN): The importance of the β-agostic interactions

Heitor A. De Abreu, Wagner B. De Almeida, Hélio A. Duarte, Gerd Fischer, Thomas Heine, Gabriel Merino, Gotthard Seifert

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Theoretical studies of the propagation barrier of ethylene polymerization with TiR2 (R=OCH3 or CN) have been performed by means of B3LYP, MP2 and MP4(SDQ) levels of theory. The aim of this work is to understand the influence of the ligand with rather different electronic properties. The cyano group is a withdrawing electronic density group, while the methoxy group is a donor group. The energy profiles obtained by our calculations show, surprisingly, that the opposite nature of the ligand groups does not influence the behavior of the catalyst significantly. In order to better characterize the β-agostic interaction, the topological analysis of the electron density (TAED) has been performed for reactants and intermediates. Although the typical CH⋯Ti agostic contacts are observed during the whole reaction, the TAED indicates that the transition complex is topologically unstable. A molecular orbital analysis shows that the the CH⋯Ti interaction plays an important role in the first step of the polymerization process, while the second step is dominated by a Ti⋯Cβ interaction.

Original languageEnglish
Pages (from-to)9-15
Number of pages7
JournalJournal of Molecular Structure: THEOCHEM
Issue number1-3
Publication statusPublished - 2006 Apr 2

Bibliographical note

Funding Information:
This work has been supported by the joint CAPES-DAAD program PROBRAL, by the Deutsche Forschungsgemeinschaft (DFG) and the Brazilian agencies Conselho Nacional para o Desenvolvimento Científico e Tecnológico (CNPq) and Fundação de Amparo a Pesquisa do Estado de Minas Gerais (FAPEMIG).

All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Condensed Matter Physics
  • Physical and Theoretical Chemistry


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