Studies of Ligand and Solvent Effects in the Alternating Copolymerization of Carbon Monoxide and Ethene by Palladium-Diphosphine Catalysis (Articolo in rivista)

Type
Label
  • Studies of Ligand and Solvent Effects in the Alternating Copolymerization of Carbon Monoxide and Ethene by Palladium-Diphosphine Catalysis (Articolo in rivista) (literal)
Anno
  • 2002-01-01T00:00:00+01:00 (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#doi
  • 10.1021/om020461o (literal)
Alternative label
  • Bianchini, Claudio; Meli, Andrea; Mueller, Gaby; Oberhauser, Werner; Passaglia, Elisa (2002)
    Studies of Ligand and Solvent Effects in the Alternating Copolymerization of Carbon Monoxide and Ethene by Palladium-Diphosphine Catalysis
    in Organometallics
    (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#autori
  • Bianchini, Claudio; Meli, Andrea; Mueller, Gaby; Oberhauser, Werner; Passaglia, Elisa (literal)
Pagina inizio
  • 4965 (literal)
Pagina fine
  • 4977 (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#numeroVolume
  • 21 (literal)
Rivista
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#descrizioneSinteticaDelProdotto
  • L'articolo descrive la formazione di copolimeri di ossido di carbonio ed etilene, promossa da un catalizzatore Pd-difosfina. Data l'importanza di questi materiali, la comprensione del meccanismo di reazione di formazione del polimero, può portare allo sviluppo di nuovi e più efficienti catalizzatori. Reazioni condotte in batch ed esperimenti in situ NMR mostrano che la presenza e/o la stereochimica di un gruppo metilico nella posizione 1-3 del legante difenilfosfinopropano (ddp) non esercita nessuna influenza sull'attività catalitica. Al contrario, la produttività è influenzata significativamente dalla formazione e stabilità di idrossospecie e bis-chelati complessi che si formano durante la reazione di ottenimento del polichetone. (literal)
Note
  • ISI Web of Science (WOS) (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#affiliazioni
  • ICCOM-CNR (literal)
Titolo
  • Studies of Ligand and Solvent Effects in the Alternating Copolymerization of Carbon Monoxide and Ethene by Palladium-Diphosphine Catalysis (literal)
Abstract
  • The Pd(II) methyl complexes [Pd(Me)(MeCN)(P-P)]PF6 are effective catalyst precursors for the alternating copolymerization of carbon monoxide with ethene in CH2Cl2 (P-P ) 1,3- bis(diphenylphosphino)propane (dppp), meso-2,4-bis(diphenylphosphino)pentane (meso-bdpp), rac-2,4-bis(diphenylphosphino)pentane (rac-bdpp)). The productivity in high molecular weight polyketones within 30 min follows the ligand order dppp > meso-bdpp > rac-bdpp. All the methyl precursors exhibit comparable values of both intrinsic activity and energy barriers to migratory insertions [Pd(Me)(CO), Pd(COMe)(C2H4)] as well as opening of â-chelates [Pd- (CH2CH2C(O)Me)(P-P)]+ by CO. It is concluded that the presence and/or stereochemistry of methyl groups in the 1,3-positions of dppp do not exert a significant influence on the propagation rate of the copolymerization reaction in CH2Cl2. High-pressure NMR studies under catalytic conditions show the occurrence of chain transfer by protonolysis with adventitious water to give í-hydroxo compounds [Pd(í-OH)(P-P)]2 2+. With time, the bischelates [Pd(P-P)2]2+ are the only species visible on the NMR time scale. Independent copolymerization reactions in CH2Cl2 with either í-OH or bis-chelate precursors show that both resting states can reenter the catalysis cycle to give alternating polyketones with productivities increasing in the orders [Pd(í-OH)(rac-bdpp)]2 2+ < [Pd(í-OH)(meso-bdpp)]2 2+ < [Pd(í-OH)(dppp)]2 2+, and [Pd(rac-bdpp)2]2+ < [Pd(dppp)2]2+ < [Pd(meso-bdpp)2]2+. On the basis of the batch reactions and in situ NMR experiments it is suggested that both í-hydroxo and bis-chelate compounds contribute appreciably to determine the overall productivity of the methyl precursors [Pd(Me)(MeCN)(P-P)]+ in CH2Cl2. The bis-chelates are also active catalysts for the CO/ethene copolymerization in MeOH with productivities that increase in the ligand order dppp , rac-bdpp < meso-bdpp. (literal)
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