Uranium(IV) alkyl cations: synthesis, ...
Type de document :
Compte-rendu et recension critique d'ouvrage
DOI :
Titre :
Uranium(IV) alkyl cations: synthesis, structures, comparison with thorium(IV) analogues, and the influence of arene-coordination on thermal stability and ethylene polymerization activity
Auteur(s) :
Andreychuk, Nicholas [Auteur]
Vidjayacoumar, Balamurugan [Auteur]
Price, Jeffrey [Auteur]
Kervazo, Sophie [Auteur]
Physico-Chimie Moléculaire Théorique [PCMT]
Peeples, Craig [Auteur]
Emslie, David [Auteur correspondant]
Vallet, Valérie [Auteur correspondant]
Physico-Chimie Moléculaire Théorique [PCMT]
Severo Pereira Gomes, Andre [Auteur]
Physico-Chimie Moléculaire Théorique [PCMT]
Réal, Florent [Auteur]
Physico-Chimie Moléculaire Théorique [PCMT]
Schreckenbach, Georg [Auteur correspondant]
University of Manitoba [Winnipeg]
Ayers, Paul [Auteur]
Vargas-Baca, Ignacio [Auteur]
Jenkins, Hilary [Auteur]
Britten, James [Auteur]
Vidjayacoumar, Balamurugan [Auteur]
Price, Jeffrey [Auteur]
Kervazo, Sophie [Auteur]
Physico-Chimie Moléculaire Théorique [PCMT]
Peeples, Craig [Auteur]
Emslie, David [Auteur correspondant]
Vallet, Valérie [Auteur correspondant]
Physico-Chimie Moléculaire Théorique [PCMT]
Severo Pereira Gomes, Andre [Auteur]
Physico-Chimie Moléculaire Théorique [PCMT]
Réal, Florent [Auteur]
Physico-Chimie Moléculaire Théorique [PCMT]
Schreckenbach, Georg [Auteur correspondant]
University of Manitoba [Winnipeg]
Ayers, Paul [Auteur]
Vargas-Baca, Ignacio [Auteur]
Jenkins, Hilary [Auteur]
Britten, James [Auteur]
Titre de la revue :
Chemical Science
Pagination :
13748-13763
Éditeur :
The Royal Society of Chemistry
Date de publication :
2022-11-10
ISSN :
2041-6520
Discipline(s) HAL :
Chimie/Chimie de coordination
Chimie/Catalyse
Chimie/Cristallographie
Chimie/Polymères
Chimie/Chimie théorique et/ou physique
Chimie/Catalyse
Chimie/Cristallographie
Chimie/Polymères
Chimie/Chimie théorique et/ou physique
Résumé en anglais : [en]
Reaction of [(XA<sub>2</sub>)U(CH<sub>2</sub>SiMe<sub>3</sub>)<sub>2</sub>] (<b>1</b>; XA<sub>2</sub> = 4,5-bis(2,6-diisopropylanilido)-2,7-di-tert-butyl-9,9- dimethylxanthene) with 1 equivalent of [Ph<sub>3</sub>C][B(C< ...
Lire la suite >Reaction of [(XA<sub>2</sub>)U(CH<sub>2</sub>SiMe<sub>3</sub>)<sub>2</sub>] (<b>1</b>; XA<sub>2</sub> = 4,5-bis(2,6-diisopropylanilido)-2,7-di-tert-butyl-9,9- dimethylxanthene) with 1 equivalent of [Ph<sub>3</sub>C][B(C<sub>6</sub>F<sub>5</sub>)<sub>4</sub>] in arene solvents afforded the arene-coordinated uranium alkyl cations, [(XA<sub>2</sub>)U(CH<sub>2</sub>SiMe<sub>3</sub>)(hn-arene)][B(C<sub>6</sub>F<sub>5</sub>)<sub>4</sub>] {arene = benzene (<b>2</b>), toluene (<b>3</b>), bromobenzene (<b>4</b>) and fluorobenzene (<b>5</b>)}. Compounds <b>2</b>, <b>3</b>, and <b>5</b> were crystallographically characterized, and in all cases the arene is π-coordinated. Solution NMR studies of <b>2-5</b> suggest that the binding preferences of the [(XA<sub>2</sub>)U(CH<sub>2</sub>SiMe<sub>3</sub>)]<sup>+</sup> cation follow the order: toluene ≈ benzene > bromobenzene > fluorobenzene. Compounds <b>2-4</b> generated in C<sub>6</sub>H<sub>5</sub>R (R = H, Me or Br, respectively) showed no polymerization activity under 1 atm of ethylene. By contrast, <b>5</b> and <b>5-Th</b> (the thorium analogue of <b>5</b>) in fluorobenzene at 20 and 70 °C achieved ethylene polymerization activities between 16 800 and 139 200 g mol<sup>-1</sup> h<sup>-1</sup> atm<sup>-1</sup>, highlighting the extent to which common arene solvents such as toluene can suppress ethylene polymerization activity in sterically open f-element complexes. However, activation of [(XA<sub>2</sub>) An(CH<sub>2</sub>SiMe<sub>3</sub>)<sub>2</sub>] {M = U (<b>1</b>) or Th (<b>1-Th</b>)} with [Ph<sub>3</sub>C][B(C<sub>6</sub>F<sub>5</sub>)<sub>4</sub>] in n-alkane solvents did not afford an active polymerization catalyst due to catalyst decomposition, illustrating the critical role of PhX (X = H, Me, Br or F) coordination for alkyl cation stabilization. Gas phase DFT calculations, including fragment interaction calculations with energy decomposition and ETS-NOCV analysis, were carried out on the cationic portion of <b>2'-Th</b>, <b>2'</b>, <b>3'</b> and <b>5'</b> (analogues of <b>2-Th</b>, <b>2</b>, <b>3</b> and <b>5</b> with hydrogen atoms in place of ligand backbone methyl and tert-butyl groups), providing insight into the nature of actinide–arene bonding, which decreases in strength in the order <b>2'-Th</b> > <b>2'</b> ≈ <b>3'</b> > <b>5'</b>.Lire moins >
Lire la suite >Reaction of [(XA<sub>2</sub>)U(CH<sub>2</sub>SiMe<sub>3</sub>)<sub>2</sub>] (<b>1</b>; XA<sub>2</sub> = 4,5-bis(2,6-diisopropylanilido)-2,7-di-tert-butyl-9,9- dimethylxanthene) with 1 equivalent of [Ph<sub>3</sub>C][B(C<sub>6</sub>F<sub>5</sub>)<sub>4</sub>] in arene solvents afforded the arene-coordinated uranium alkyl cations, [(XA<sub>2</sub>)U(CH<sub>2</sub>SiMe<sub>3</sub>)(hn-arene)][B(C<sub>6</sub>F<sub>5</sub>)<sub>4</sub>] {arene = benzene (<b>2</b>), toluene (<b>3</b>), bromobenzene (<b>4</b>) and fluorobenzene (<b>5</b>)}. Compounds <b>2</b>, <b>3</b>, and <b>5</b> were crystallographically characterized, and in all cases the arene is π-coordinated. Solution NMR studies of <b>2-5</b> suggest that the binding preferences of the [(XA<sub>2</sub>)U(CH<sub>2</sub>SiMe<sub>3</sub>)]<sup>+</sup> cation follow the order: toluene ≈ benzene > bromobenzene > fluorobenzene. Compounds <b>2-4</b> generated in C<sub>6</sub>H<sub>5</sub>R (R = H, Me or Br, respectively) showed no polymerization activity under 1 atm of ethylene. By contrast, <b>5</b> and <b>5-Th</b> (the thorium analogue of <b>5</b>) in fluorobenzene at 20 and 70 °C achieved ethylene polymerization activities between 16 800 and 139 200 g mol<sup>-1</sup> h<sup>-1</sup> atm<sup>-1</sup>, highlighting the extent to which common arene solvents such as toluene can suppress ethylene polymerization activity in sterically open f-element complexes. However, activation of [(XA<sub>2</sub>) An(CH<sub>2</sub>SiMe<sub>3</sub>)<sub>2</sub>] {M = U (<b>1</b>) or Th (<b>1-Th</b>)} with [Ph<sub>3</sub>C][B(C<sub>6</sub>F<sub>5</sub>)<sub>4</sub>] in n-alkane solvents did not afford an active polymerization catalyst due to catalyst decomposition, illustrating the critical role of PhX (X = H, Me, Br or F) coordination for alkyl cation stabilization. Gas phase DFT calculations, including fragment interaction calculations with energy decomposition and ETS-NOCV analysis, were carried out on the cationic portion of <b>2'-Th</b>, <b>2'</b>, <b>3'</b> and <b>5'</b> (analogues of <b>2-Th</b>, <b>2</b>, <b>3</b> and <b>5</b> with hydrogen atoms in place of ligand backbone methyl and tert-butyl groups), providing insight into the nature of actinide–arene bonding, which decreases in strength in the order <b>2'-Th</b> > <b>2'</b> ≈ <b>3'</b> > <b>5'</b>.Lire moins >
Langue :
Anglais
Vulgarisation :
Non
Projet ANR :
Source :
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