The effect of the catalyst structure on the stereoselectivity of CO/vinyl arene copolymerization has been studied with the aim of developing catalytic systems able to improve the yields while maintaining the high degree of copolymer isotacticity previously obtained using achiral nitrogen ligands. Aryl alpha-diimine ligands having extended aromatic rings (Ar)2DABMe2, with Ar = 1-C10H7 (e), 1-C14H9 (f), 9-C14H9 (g), have been synthesized, and alpha-diimine coordination to cationic methylpalladium complexes has been investigated in solution, by means of NMR spectroscopy, and in the solid state for [Pd(Me)(NCMe)((9-C14H9)2DABMe2)][PF6] (2g). The performance of these catalysts in CO/vinyl arene copolymerization, under mild conditions, was analyzed in terms of productivity and degree of stereoregularity of the resulting polyketones. In comparison with previous results, a remarkable enhancement in the yield of isotactic copolymer was observed using the new achiral 9-anthryl alpha-diimine ligand g, confirming that the ortho disubstitution and the extended aromatic rings play key roles in obtaining good stereoselectivity and good productivity. To perform a structural analysis of the first steps of the CO/p-methylstyrene copolymerization, complex [Pd(Me)(CO)((9-C14H9)2DABMe2)][BAr′4] (3g) was used as a starting point: NMR investigation reveals the stereoselective formation of the olefin/CO/olefin insertion product (6g), which prevalently exists in solution in only one diastereoisomeric form, thus justifying the observed high polymer isotacticity.
New Aryl alpha-Diimine Palladium(II) Catalysts in Stereocontrolled CO/Vinyl Arene Copolymerization / Carfagna, Carla; Gatti, Giuseppe; Paoli, Paola; Binotti, Barbara; Fini, Francesco; Passeri, Alessandra; Rossi, Patrizia; Gabriele, Bartolo. - In: ORGANOMETALLICS. - ISSN 0276-7333. - ELETTRONICO. - 33:1(2014), pp. 129-144. [10.1021/om400887x]
New Aryl alpha-Diimine Palladium(II) Catalysts in Stereocontrolled CO/Vinyl Arene Copolymerization
FINI, Francesco;
2014
Abstract
The effect of the catalyst structure on the stereoselectivity of CO/vinyl arene copolymerization has been studied with the aim of developing catalytic systems able to improve the yields while maintaining the high degree of copolymer isotacticity previously obtained using achiral nitrogen ligands. Aryl alpha-diimine ligands having extended aromatic rings (Ar)2DABMe2, with Ar = 1-C10H7 (e), 1-C14H9 (f), 9-C14H9 (g), have been synthesized, and alpha-diimine coordination to cationic methylpalladium complexes has been investigated in solution, by means of NMR spectroscopy, and in the solid state for [Pd(Me)(NCMe)((9-C14H9)2DABMe2)][PF6] (2g). The performance of these catalysts in CO/vinyl arene copolymerization, under mild conditions, was analyzed in terms of productivity and degree of stereoregularity of the resulting polyketones. In comparison with previous results, a remarkable enhancement in the yield of isotactic copolymer was observed using the new achiral 9-anthryl alpha-diimine ligand g, confirming that the ortho disubstitution and the extended aromatic rings play key roles in obtaining good stereoselectivity and good productivity. To perform a structural analysis of the first steps of the CO/p-methylstyrene copolymerization, complex [Pd(Me)(CO)((9-C14H9)2DABMe2)][BAr′4] (3g) was used as a starting point: NMR investigation reveals the stereoselective formation of the olefin/CO/olefin insertion product (6g), which prevalently exists in solution in only one diastereoisomeric form, thus justifying the observed high polymer isotacticity.File | Dimensione | Formato | |
---|---|---|---|
24 - Organometallics 2014 Carfagna 129-144.pdf
Accesso riservato
Descrizione: Articolo Principale
Tipologia:
Versione pubblicata dall'editore
Dimensione
2.71 MB
Formato
Adobe PDF
|
2.71 MB | Adobe PDF | Visualizza/Apri Richiedi una copia |
Pubblicazioni consigliate
I metadati presenti in IRIS UNIMORE sono rilasciati con licenza Creative Commons CC0 1.0 Universal, mentre i file delle pubblicazioni sono rilasciati con licenza Attribuzione 4.0 Internazionale (CC BY 4.0), salvo diversa indicazione.
In caso di violazione di copyright, contattare Supporto Iris