Stereoselectivity in Butadiene Polymerization Promoted by Using Ziegler–Natta Catalysts Based on (Anilidomethyl)pyridine Group (IV) Complexes
The stereoselective polymerization of conjugated dienes promoted by using transition metal complexes has attracted much interest in both industrial and academic environments for the relevance of polydienes as synthetic rubbers and for the challenging reaction mechanisms. Among the different transiti...
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MDPI AG
2023-12-01
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| Series: | Symmetry |
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| Online Access: | https://www.mdpi.com/2073-8994/16/1/18 |
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| author | Stefano Milione Stefania Pragliola |
| author_facet | Stefano Milione Stefania Pragliola |
| author_sort | Stefano Milione |
| collection | DOAJ |
| description | The stereoselective polymerization of conjugated dienes promoted by using transition metal complexes has attracted much interest in both industrial and academic environments for the relevance of polydienes as synthetic rubbers and for the challenging reaction mechanisms. Among the different transition metal complexes, those based on group IV have been demonstrated to be versatile and efficient catalysts. Titanium complexes are generally more active than zirconium complexes. A rare exception to this trend is represented by a series of Zr(IV) complexes supported by (anilidomethyl)pyridine ligands that, after activation by using Al(iBu<sub>2</sub>H)/MAO, were found to be highly active affording exclusively <i>cis</i>-1,4-polybutadiene. To rationalize this unexpected trend and to obtain more insights into the parameters that control the reactivity of group IV complexes, a theoretical investigation of the entire polymerization mechanism, employing density functional methods, was undertaken. In the framework of the widely accepted polymerization scheme, the different intermediates featuring h<sup>4</sup> (both <i>cis</i> and <i>trans</i>) coordination of the monomer and h<sup>1</sup> or h<sup>3</sup> (<i>syn</i> or <i>anti</i>)allyl coordination of the growing chain were scrutinized. Subsequently, the effects of the metal center on the free-energy profiles of the elementary steps involved in the reaction were examined. The results presented herein aim to achieve a better knowledge of the influence of the metal on the polymerization rates and on the stereoselectivity of the reaction. |
| first_indexed | 2024-03-08T10:34:03Z |
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| id | doaj.art-0c88c4d8e3144be38ca810e53f218e3a |
| institution | Directory Open Access Journal |
| issn | 2073-8994 |
| language | English |
| last_indexed | 2024-03-08T10:34:03Z |
| publishDate | 2023-12-01 |
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| spelling | doaj.art-0c88c4d8e3144be38ca810e53f218e3a2024-01-26T18:38:32ZengMDPI AGSymmetry2073-89942023-12-011611810.3390/sym16010018Stereoselectivity in Butadiene Polymerization Promoted by Using Ziegler–Natta Catalysts Based on (Anilidomethyl)pyridine Group (IV) ComplexesStefano Milione0Stefania Pragliola1Department of Chemistry, University of Salerno, Via Giovanni Paolo II, 84084 Fisciano, Salerno, ItalyDepartment of Chemistry, University of Salerno, Via Giovanni Paolo II, 84084 Fisciano, Salerno, ItalyThe stereoselective polymerization of conjugated dienes promoted by using transition metal complexes has attracted much interest in both industrial and academic environments for the relevance of polydienes as synthetic rubbers and for the challenging reaction mechanisms. Among the different transition metal complexes, those based on group IV have been demonstrated to be versatile and efficient catalysts. Titanium complexes are generally more active than zirconium complexes. A rare exception to this trend is represented by a series of Zr(IV) complexes supported by (anilidomethyl)pyridine ligands that, after activation by using Al(iBu<sub>2</sub>H)/MAO, were found to be highly active affording exclusively <i>cis</i>-1,4-polybutadiene. To rationalize this unexpected trend and to obtain more insights into the parameters that control the reactivity of group IV complexes, a theoretical investigation of the entire polymerization mechanism, employing density functional methods, was undertaken. In the framework of the widely accepted polymerization scheme, the different intermediates featuring h<sup>4</sup> (both <i>cis</i> and <i>trans</i>) coordination of the monomer and h<sup>1</sup> or h<sup>3</sup> (<i>syn</i> or <i>anti</i>)allyl coordination of the growing chain were scrutinized. Subsequently, the effects of the metal center on the free-energy profiles of the elementary steps involved in the reaction were examined. The results presented herein aim to achieve a better knowledge of the influence of the metal on the polymerization rates and on the stereoselectivity of the reaction.https://www.mdpi.com/2073-8994/16/1/18diene polymerizationZiegler–Natta catalystDFT calculation |
| spellingShingle | Stefano Milione Stefania Pragliola Stereoselectivity in Butadiene Polymerization Promoted by Using Ziegler–Natta Catalysts Based on (Anilidomethyl)pyridine Group (IV) Complexes Symmetry diene polymerization Ziegler–Natta catalyst DFT calculation |
| title | Stereoselectivity in Butadiene Polymerization Promoted by Using Ziegler–Natta Catalysts Based on (Anilidomethyl)pyridine Group (IV) Complexes |
| title_full | Stereoselectivity in Butadiene Polymerization Promoted by Using Ziegler–Natta Catalysts Based on (Anilidomethyl)pyridine Group (IV) Complexes |
| title_fullStr | Stereoselectivity in Butadiene Polymerization Promoted by Using Ziegler–Natta Catalysts Based on (Anilidomethyl)pyridine Group (IV) Complexes |
| title_full_unstemmed | Stereoselectivity in Butadiene Polymerization Promoted by Using Ziegler–Natta Catalysts Based on (Anilidomethyl)pyridine Group (IV) Complexes |
| title_short | Stereoselectivity in Butadiene Polymerization Promoted by Using Ziegler–Natta Catalysts Based on (Anilidomethyl)pyridine Group (IV) Complexes |
| title_sort | stereoselectivity in butadiene polymerization promoted by using ziegler natta catalysts based on anilidomethyl pyridine group iv complexes |
| topic | diene polymerization Ziegler–Natta catalyst DFT calculation |
| url | https://www.mdpi.com/2073-8994/16/1/18 |
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