Two pyrene-tagged iminopyridines (N-N') were used to synthesize neutral and monocationic, palladium(II) complexes, [Pd(Me)Cl(N-N')] and [Pd(Me)(MeCN)(N-N')][PF6]. The monocationic complexes generated active catalysts in the CO/vinyl arene copolymerization leading to polyketones with yields and molecular weight strongly dependent on N-N', being the ketimine catalysts one order of magnitude more productive than the aldimine counterpart. The stereochemistry of polyketones synthesized with the aldimine catalyst was found to be dependent on the vinyl comonomer: prevailingly syndiotactic copolymers were obtained for styrene, prevailingly isotactic copolymers were produced for 4-methyl styrene, and atactic macromolecules were formed for the 4-tbutyl styrene. The statistical analysis demonstrated that the control of the stereochemistry switched from enantioselective site control for 4-methyl styrene to a combination of chain-end and enantioselective site control for styrene.

Unprecedented comonomer dependence of the stereochemistry control in Pd-catalyzed CO/vinyl arene polyketone synthesis

ROSAR, VERA;DALLA MARTA, SILVIA;MILANI, Barbara
2015

Abstract

Two pyrene-tagged iminopyridines (N-N') were used to synthesize neutral and monocationic, palladium(II) complexes, [Pd(Me)Cl(N-N')] and [Pd(Me)(MeCN)(N-N')][PF6]. The monocationic complexes generated active catalysts in the CO/vinyl arene copolymerization leading to polyketones with yields and molecular weight strongly dependent on N-N', being the ketimine catalysts one order of magnitude more productive than the aldimine counterpart. The stereochemistry of polyketones synthesized with the aldimine catalyst was found to be dependent on the vinyl comonomer: prevailingly syndiotactic copolymers were obtained for styrene, prevailingly isotactic copolymers were produced for 4-methyl styrene, and atactic macromolecules were formed for the 4-tbutyl styrene. The statistical analysis demonstrated that the control of the stereochemistry switched from enantioselective site control for 4-methyl styrene to a combination of chain-end and enantioselective site control for styrene.
File in questo prodotto:
File Dimensione Formato  
cctc.201500498_proofs.pdf

embargo fino al 24/06/2016

Descrizione: articolo principale
Tipologia: Bozza finale post-referaggio (post-print)
Licenza: Creative commons
Dimensione 667.88 kB
Formato Adobe PDF
667.88 kB Adobe PDF Visualizza/Apri
Unprecedented comonomer dependence of the stereochemistry control in Pd-catalyzed CO-vinyl arene polyketone synthesis.pdf

non disponibili

Descrizione: pdf editoriale
Tipologia: Documento in Versione Editoriale
Licenza: Digital Rights Management non definito
Dimensione 804.23 kB
Formato Adobe PDF
804.23 kB Adobe PDF   Visualizza/Apri   Richiedi una copia

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11368/2842715
Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 13
  • ???jsp.display-item.citation.isi??? 14
social impact