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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Electronic vs. Steric Hindrance Effects in Amine Ligands to Ru-Based Initiators for ROMP

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Author(s):
Silva, Tiago B. [1] ; Camargo, Ricardo S. [1] ; Lima-Neto, Benedito S. [1]
Total Authors: 3
Affiliation:
[1] Univ Sao Paulo, Inst Quim Sao Carlos, BR-13560970 Sao Carlos, SP - Brazil
Total Affiliations: 1
Document type: Journal article
Source: Journal of the Brazilian Chemical Society; v. 25, n. 12, SI, p. 2425-2432, DEC 2014.
Web of Science Citations: 2
Abstract

Complexos do tipo {[}RuCl2(PPh3)(2)(amina) x], com NH2Ph (1; x = 2), NH(2)Bz (2; x = 2) and NHBuPh (3; x = 1) na presenca de etildiazoacetato (EDA), foram aplicados em reacoes de polimerizacao via metatese por abertura de anel (ROMP) de norborneno (NBE), norbornadieno (NBD) e diciclopentadieno (DCPD). Rendimentos quantitativos de poliNBE foram obtidos a 50 degrees C por 30 min usando 1 e por 5 min usando 2. Isso ocorreu a 25 degrees C por 5 min quando foi usado 3. Os valores do indice de polidispersidade (PDI) variaram de 3,5 a 1,6 (M-w = 104-105 g mol(-1)). O complexo 3 foi ativo para ROMP de NBD e DCPD, bem como para copolimerizacao de NBE com NBD ou com DCPD. O maior carater s-doador de NH(2)Bz em 2, em relacao a NH2Ph em 1, favoreceu a reatividade do complexo 2 que e hexacoordenado como 1. O angulo de cone de NHBuPh definiu a pentacoordenacao em 3 e a sua melhor reatividade para ROMP, apesar do baixo carater s-doador como o de NH2Ph. {[}RuCl2(PPh3)(2)(amine) x]-type complexes, with NH2Ph (1; x = 2), NH(2)Bz (2; x = 2) and NHBuPh (3; x = 1) in the presence of ethyldiazoacetate (EDA), were investigated for ring opening metathesis polymerization (ROMP) of norbornene (NBE), norbornadiene (NBD) and dicyclopentadiene (DCPD). Quantitative yields of polyNBE were obtained at 50 degrees C for 30 min with 1 and for 5 min with 2, whereas this occurred at 25 degrees C for 5 min with 3. Polydispersity index (PDI) values ranged from 3.5 to 1.6 (M-w = 104-105 g mol(-1)). Complex 3 was active for ROMP of NBD and DCPD, as well as for copolymerizations of NBE with either NBD or DCPD. The high s-donor character of NH(2)Bz favored the reactivity of the six-coordinated complex 2, contrary to complex 1. The large cone angle of NHBuPh defined the five-coordination in 3 and the best reactivity for ROMP, in spite of the low s-donor character as in NH2Ph. (AU)