Structural and kinetic insights into the mechanism for ring opening metathesis polymerization of norbornene with [RuCl2(PPh3)(2)(piperidine)] as initiator complex

Autor(es)

Fernandes, Ronaldo J. ^[1] ; Silva, Tiago B. ^[1] ; Lima-Neto, Benedito S. ^[1] ; Haiduke, Roberto L. A. ^[1]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Inst Quim Sao Carlos, BR-13560970 Sao Carlos, SP - Brazil

• Tipo de documento: Artigo Científico
• Fonte: JOURNAL OF MOLECULAR CATALYSIS A-CHEMICAL; v. 410, p. 58-65, DEC 15 2015.
• Citações Web of Science: 6

Resumo

This investigation combines theoretical results and experimental data to elucidate the main kinetic and mechanism for the ring opening metathesis polymerization of norbornene by means of the {[}RuCl2(PPh3)(2)(piperidine)] complex as catalyst initiator. Structural species were defined and a kinetic profile of the entire reaction is depicted. The determined mechanism showed an associative reaction between the {[}RuCl2(PPh3)(2)(piperidine)] complex initiator and ethyl diazoacetate as the first step, resulting in a metal-carbene species. This species loses one triphenylphosphine molecule (PPh3) and the global rate-determining step is associated with a removal of the second PPh3 molecule due to an electronic trans-synergism between piperidine and this PPh3 molecule. Entropic factors are crucial to the spontaneity observed for the dissociation of both PPh3 ligands. The step following the rate-determining one is associated with the binding of a norbornene molecule and a similar trans-synergism between this monomer and piperidine activates the catalysis. This electronic effect maintains the system in a very important conformation along the catalytic chain. (C) 2015 Elsevier B.V. All rights reserved. (AU)

• Processo FAPESP: 06/57577-4 - Uso de combinações de ligantes ancilares de P(III), N(III), e S(II ou IV) no desenvolvimento de catalisadores de Ru(II) para polimerização via metátese de olefinas
• Beneficiário: Benedito dos Santos Lima Neto
• Modalidade de apoio: Auxílio à Pesquisa - Regular
• Processo FAPESP: 10/18743-1 - Uso de multipolos da teoria quântica de átomos em moléculas e estudos cinéticos em sistemas encontrados no meio interestelar
• Beneficiário: Roberto Luiz Andrade Haiduke
• Modalidade de apoio: Auxílio à Pesquisa - Regular