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Journal ArticleDOI

W(CO)6/CBr4/hv — a new system for metathesis polymerisation

14 Jan 1997-Journal of Molecular Catalysis A-chemical (Elsevier)-Vol. 115, Iss: 1, pp 79-84
TL;DR: In this paper, an optimization study of W(CO) 6 CBr 4 / hv is presented, where the active species are characterised by reaction with acetophenone and copolymers of phenylacetylene and norbornene.
Abstract: Metathesis polymerisation can be effected with many catalysts under a variety of conditions. The system described here, viz., W(CO) 6 CBr 4 / hv , induces polymerisation by in situ generation of the active species and has not been reported in the literature so far. In this paper, optimisation studies of this system, yields obtained with various monomers and characterisation of the active species are discussed. Variation of different parameters such as the ratio of W(CO) 6 :CBr 4 , the time of photolysis and the effect of solvents as well as that of the metal carbonyls have been studied. In addition, copolymers of phenylacetylene and norbornene have been synthesised. We have also attempted to characterise the active species responsible for the polymerisation by reaction with acetophenone.
Citations
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Journal ArticleDOI
TL;DR: The structure of the polymers obtained with either 1 or 2 are similar to those found in the corresponding polymers prepared by the action of [Ru(CF(3)SO(3))(2)(IMesH(2))(CH-2-(2-PrO)-C(6)H(4))], which strongly suggest the formation of Ru-based Grubbs-type initiators in the course of the UV-based activation process.
Abstract: A series of cationic and neutral Ru II complexes of the general formula [Ru(L)(X) (tBuCN) 4 ] + X ― and [Ru(L)(X) 2 (tBuCN) 3 )], that is, [Ru-(CF 3 SO 3 ){NCC(CH 3 ) 3 } 4 (IMesH 2 )] + [CF 3 SO 3 ] ― (1), [Ru(CF 3 SO 3 ){NCC-(CH 3 ) 3 } 4 (IMes)] + [CF 3 SO 3 ] ― (2), [RuCl-{NCC(CH 3 ) 3 } 4 (IMes)] + Cl ― (3), [RuCl-{NCC(CH 3 ) 3 } 4 (IMesH 2 ) + Cl ― ]/[RuCl 2 -{NCC(CH 3 ) 3 } 3 (IMesH 2 )] (4), and [Ru-(NCO) 2 {NCC(CH 3 ) 3 } 3 (IMesH 2 )] (5) (IMes = 1,3-dimesitylimidazol-2-ylidene, IMesH 2 =1,3-dimesityl-imidazolin-2-ylidene) have been synthesized and used as UV-triggered precatalysts for the ring-opening metathesis polymerization (ROMP) of different norborn-2-ene- and cis-cyclooctene-based monomers. The absorption maxima of complexes 1―5 were in the range of 245―255 nm and thus perfectly fit the emission band of the 254 nm UV source that was used for activation. Only the cationic Ru"-complexes based on ligands capable of forming μ 2 -complexes such as 1 and 2 were found to be truly photolatent in ROMP. In contrast, complexes 3―5 could be activated by UV light; however, they also showed a low but significant ROMP activity in the absence of UV light. As evidenced by 1 H and 13 C NMR spectroscopy, the structure of the polymers obtained with either 1 or 2 are similar to those found in the corresponding polymers prepared by the action of [Ru(CF 3 SO 3 ) 2 (IMesH 2 )(CH-2-(2-PrO)-C 6 H 4 )], which strongly suggest the formation of Ru-based Grubbs-type initiators in the course of the UV-based activation process. Precatalysts that have the IMesH 2 ligand showed significantly enhanced reactivity as compared with those based on the IMes ligand, which is in accordance with reports on the superior reactivity of IMesH 2 -based Grubbs-type catalysts compared with IMes-based systems.

43 citations

Journal ArticleDOI
TL;DR: In this paper, four chiral enantiomerically pure monomers, exo,exo-N, N-(norborn-5-ene-2,3-dicarbimido)-L-valine-tert-butylamide (endo-2), were subjected to ring-opening metathesis polymerization (ROMP) with Ru(CF3CO2)2(IMesH2)(p-cymene)
Abstract: Four chiral, enantiomerically pure monomers, exo,exo-N,N-(norborn-5-ene-2,3-dicarbimido)-L-valine ethyl ester (exo-1),endo,endo-N,N-(norborn-5-ene-2,3-dicarbimido)-L-valineethyl ester (endo-1), exo,exo-N,N-(norborn-5-ene-2,3-dicarbimido)-L-valine-tert-butylamide (exo-2), and endo,endo-N,N-(norborn-5-ene-2,3-dicarbimido)-L-valine-tert-butylamide (endo-2), were subjected to ring-opening metathesis polymerization (ROMP) with Ru(CF3CO2)2(IMesH2)(p-cymene) (3), Ru(CF3CO2)2(IMes)(p-cymene) (4), RuCl2(IMes)(p-cymene) (5), Ru(PCy3)(CF3CO2)2(p-cymene) (6), Ru(CF3CO2)2(p-cymene)·CF3COOAgPCy3 (6a), Ru(CF3CO2)2(PPh3)(p-cymene) (7), Ru(CF3CO2)2(IMes)(PhNC)3 (8), and Ru(CF3CO2)2(IMesH2)(PhNC)3 (9) (IMes = 1,3-dimesitylimidazol-2-ylidene, IMesH2 = 1,4-dimesityl-4,5-diyhdroimidazolin-2-ylidene, PCy3 = tricyclohexylphosphane). X-ray structures of precatalysts 3 and 6–9 are presented. Compounds 3 and 4 displayed significant ROMP activity, allowing for the controlled, yet nonliving synthesis of the corresponding polymers with polydispersity indices (PDIs) in the range of 1.17–2.14. In all cases the exo isomers of compounds 1 and 2 were polymerized by preference. While poly(endo-1) was formed in an all-trans form, poly(exo-1) and poly(exo-2) were produced in their cis/trans forms with a cis content of around 40 %. Calculations carried out at the B3LYP/LACVP* level suggest two possible mechanisms for the increased reactivity of the 2,3-R2-exo,exo isomers of norborn-5-ene-2,3-dicarbimido derivatives resulting in the formation of the ROMP-active RuIV alkylidene. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)

30 citations

Journal ArticleDOI
TL;DR: In this article, the photo-initiated ring-opening metathesis polymerization (photo-ROMP) was investigated for both norborn-2-ene and functional monomers.
Abstract: Novel ruthenium-based photoactive transition metal catalysts, i.e. [Ru(CF 3 -CO 2 ) 2 (p-cymene)(IMes)] (2), [Ru(CF 3 CO 2 ) 2 (PhNC) 3 (IMes)] (3), [Ru(CF 3 CO 2 ) 2 (p-cymene) (IMesH 2 )] (4), [Ru(CF 3 CO 2 ) 2 (PhNc)) 3 (IMesH 2 )] (5), have been prepared and investigated for their use as initiators for the thermally and photo-initiated ring-opening metathesis polymerization (photo-ROMP). The polymerization behavior of the novel systems for both norborn-2-ene and functional monomers, such as norborn-5-ene-2-ylmethanol, has been investigated.

29 citations

Journal ArticleDOI
TL;DR: In this article, a survey of Group 6 transition metal carbonyls with alkenes and the formation of alkene carbonyl complexes of the type: [M(CO)5(η2-alkene)], [M[M[CO]4[2]-2]-alkene] and [M [M]3[2] are discussed.

22 citations

References
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Journal ArticleDOI
TL;DR: Synthese de polynorbornene et poly(exodicyclopentadiene) avec un groupe terminal aldehyde par polymerisation puis reaction avec le terephtalaldehyde as discussed by the authors.
Abstract: Synthese de polynorbornene et poly(exodicyclopentadiene) avec un groupe terminal aldehyde par polymerisation puis reaction avec le terephtalaldehyde. Ce groupe terminal sert a amorcer la polycondensation du t-butyldimethylsilyl vinylether conduisant a un copolymere sequence

63 citations

Journal ArticleDOI
TL;DR: A review of titanacyclobutane-initiated "living" olefin metathesis polymerization for the preparation of new polymer structures is given in this paper, where the same type of reaction was used to link preformed polymer blocks to give ABA-type triblock copolymers and graft Copolymers.

38 citations

Journal ArticleDOI
TL;DR: In this paper, a mechanism for the formation of these compounds is outlined, and the mechanism for their formation is described in terms of the insertion of metalladichlorocarbene moieties into the carbon double bond.

35 citations

Journal ArticleDOI
TL;DR: In this article, the metathesis of internal and terminal olefins was investigated in photocatalytic systems containing tungsten compounds of the type W(CO)5L (L = CO, py, PPh3, Cl−).

27 citations

Journal ArticleDOI
TL;DR: The reaction of a metathesis catalyst prepared from W(CO) 6 /CCl 4 /hν with cyclic enol ethers gives products arising from the probable insertion of a dichlorocarbene complex of tungsten into the carbon-carbon double bond.

22 citations