Atom‐Transfer Radical Addition (ATRA) and Cyclization (ATRC) Reactions Catalyzed by a Mixture of [RuCl<sub>2</sub>Cp*(PPh<sub>3</sub>)] and Magnesium

Thommes, Katrin; Içli, Burçak; Scopelliti, Rosario; Severin, Kay

doi:10.1002/chem.200700442

Cited by 111 publications

(66 citation statements)

References 77 publications

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“…[3] Meanwhile, many transitionmetal complexes are known to promote inter-and intramolecular ATRA reactions. [1] The highest activities are typically found for copper [1,4] and ruthenium [1,[5][6][7] catalysts. One of the best catalysts described so far is the half-sandwich complex [RuCl 2 Cp*A C H T U N G T R E N N U N G (PPh 3 )] (1; Cp*= pentamethylcyclopentadienyl).…”

Section: Introductionmentioning

confidence: 98%

“…One of the best catalysts described so far is the half-sandwich complex [RuCl 2 Cp*A C H T U N G T R E N N U N G (PPh 3 )] (1; Cp*= pentamethylcyclopentadienyl). [6,7] Turnover numbers (TONs) of more than 1000 have been achieved for different substrate combinations. An additional advantage from a practical point of view is the fact that complex 1 is not air-sensitive and is easy to make.…”

Section: Introductionmentioning

confidence: 99%

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Atom‐Transfer Radical Addition Reactions Catalyzed by RuCp* Complexes: A Mechanistic Study

Fernández‐Zúmel

Thommes

Kiefer

et al. 2009

Chemistry A European J

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Kinetic and spectroscopic analyses were performed to gain information about the mechanism of atom-transfer radical reactions catalyzed by the complexes [RuCl2Cp*(PPh3)] and [RuClCp*(PPh3)2] (Cp*=pentamethylcyclopentadienyl), in the presence and in the absence of the reducing agent magnesium. The reactions of styrene with ethyl trichloroacetate, ethyl dichloroacetate, or dichloroacetonitrile were used as test reactions. The results show that for substrates with high intrinsic reactivity, such as ethyl trichloroacetate, the oxidation state of the catalyst in the resting state is +3, and that the reaction is zero-order with respect to the halogenated compound. Furthermore, the kinetic data suggest that the metal catalyst is not directly involved in the rate-limiting step of the reaction.

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Section: Introductionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

Atom‐Transfer Radical Addition Reactions Catalyzed by RuCp* Complexes: A Mechanistic Study

Fernández‐Zúmel

Thommes

Kiefer

et al. 2009

Chemistry A European J

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“…23 The mechanism of the ATRA has many similarities with ATRP, 24 so in order to prevent the gradual, irreversible, oxidation of complex 2 during its action as catalyst we decided to investigate the polymerization of styrene in the presence of two equivalents of zinc with respect to catalyst 2.…”

Section: Resultsmentioning

confidence: 99%

Comparative study of the catalytic activity of the complexes Cp*RuCl(PAr3)2 [Ar = -C6H5 and 4-CF3-C6H4] in the ATRP of styrene

Villa-Hernandez¹,

Rosales-Velázquez²,

Saldívar‐Guerra³

et al. 2011

J. Braz. Chem. Soc.

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A polimerização do estireno por ATRP foi conduzida usando os complexos Cp*RuCl(PPh 3 ) 2 , e Cp*RuCl[P(4-CF 3 −C 6 H 4 ) 3 ] 2 como catalisadores, a fim de avaliar a influência das propriedades eletrônicas dos ligantes fosfinas na velocidade e controle da polimerização. Os dados cinéticos para polimerizações realizadas com Cp*RuCl(PPh 3 ) 2 , mostram que os pesos moleculares aumentam linearmente com a conversão, com uma eficiência média de iniciação, de 0,77. Os pesos moleculares obtidos no estudo cinético com Cp*RuCl[P(4-CF 3 −C 6 H 4 ) 3 ] 2 também aumentam com a conversão, mas mostram um marcado desvio abaixo dos pesos moleculares teóricos. Este comportamento foi explicado pela oxidação gradual, irreversível do catalisador Cp*RuCl[P(4-CF 3 −C 6 H 4 ) 3 ] 2 , como confirmado pela espectroscopia de RMN de 31 P. O catalisador Cp*RuCl(PPh 3 ) 2 promove a polimerização com uma velocidade maior do que usando Cp*RuCl[P(4-CF 3 −C 6 H 4 ) 3 ] 2 , o que é consistente com as melhores propriedades de doação de elétrons de PPh 3 versus P(4-CF 3 −C 6 H 4 ) 3 . Estudos preliminares da polimerização do estireno com ATRP em CO 2 supercrítico mostram que somente o catalisador Cp*RuCl[P(4-CF 3 −C 6 H 4 ) 3 ] 2 , com ligantes fluorados, é ativo.Styrene polymerization by ATRP was conducted independently using the complexes Cp*RuCl(PPh 3 ) 2 , and Cp*RuCl[P(4-CF 3 −C 6 H 4 ) 3 ] 2 as catalysts, in order to evaluate the influence of the electronic properties of the phosphine ligands on the rate and control of the polymerization. The kinetic data for polymerizations carried out with Cp*RuCl(PPh 3 ) 2 , show that molecular weights increase linearly with conversion with an average initiation efficiency of 0.77. The molecular weights obtained in the kinetic study with Cp*RuCl[P(4-CF 3 −C 6 H 4 ) 3 ] 2 also increase with conversion but show a marked deviation below the theoretical molecular weights. This behavior was explained by the gradual, irreversible, oxidation of catalyst Cp*RuCl[P(4-CF 3 −C 6 H 4 ) 3 ] 2 as confirmed by 31 P-NMR spectroscopy. Catalyst Cp*RuCl(PPh 3 ) 2 promotes the polymerization with a rate of polymerization higher than that obtained using Cp*RuCl[P(4-CF 3 −C 6 H 4 ) 3 ] 2 ; this is consistent with the better electron donating properties of PPh 3 versus P(4-CF 3 −C 6 H 4 ) 3 . Preliminary studies of styrene polymerization by ATRP in supercritical CO 2 , shows that only catalyst Cp*RuCl[P(4-CF 3 −C 6 H 4 ) 3 ] 2 , with fluorinated ligands, was active.Keywords: atom transfer radical polymerization (ATRP), half sandwich ruthenium catalysts, styrene polymerization, supercritical carbon dioxide IntroductionHalf sandwich organometallic complexes containing transition metal from group 8 (Fe 1,2 and Ru 3-10 ) are an important group of catalysts in the polymerization of vinyl monomers by ATRP. The reversible, one electron oxidation-reduction that these complexes experience during controlled radical polymerization, promotes the establishment of a dynamic equilibrium between active and dormant species, with equilibrium con...

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“…[30,31] This strategy is based in the use of a constant source of organic free radicals to regenerate the Cu(I) activator, which is otherwise consumed in termination reactions. After this report, Severin [32] and Pintauer [33] have employed the same technique in ATRA reactions catalyzed by ruthenium and copper complexes, respectively. One of the possible reducing agents is AIBN, but the use of this compound has some problems.…”

Section: Enhanced Catalytic Activity By the Presence Of Additives: Thmentioning

confidence: 91%

“…A second agent reported by Severin and co-worker was metallic magnesium. [32] On the basis of these findings, we decided to try the use of Mg in the Kharasch addition of CCl 4 to a series of dienes (4, 5, 11 and 12), using 1 and 2 as catalyst (Scheme 8). Water was employed to activate the Mg surface.…”

Section: Enhanced Catalytic Activity By the Presence Of Additives: Thmentioning

confidence: 99%

Copper‐Catalyzed Synthesis of 1,2‐Disubstituted Cyclopentanes from 1,6‐Dienes by Ring‐Closing Kharasch Addition of Carbon Tetrachloride

2008

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The reaction of carbon tetrachloride (CCl 4 ) with various 1,6-heptadienes catalyzed by copper homoscorpionate complexes affords cyclization products in moderate to high yields. The process involves the addition of the trichloromethyl radical to the diene followed by a 5-exo-trig cyclization reaction, resulting in the formation of the cis-3-chloromethyl-4-(2,2,2-trichloroethyl)cyclopentane isomers in a highly regiospecific and stereospecific manner.We have studied the use of magnesium (Mg) as reducing agent for the regeneration of copper(I) catalysts. This method has afforded heterocycles in high yields even in the cases of diallyl ether (DAE) and tert-butyl N,N-diallylcarbamate (TBDAC).

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Atom‐Transfer Radical Addition (ATRA) and Cyclization (ATRC) Reactions Catalyzed by a Mixture of [RuCl₂Cp*(PPh₃)] and Magnesium

Cited by 111 publications

References 77 publications

Atom‐Transfer Radical Addition Reactions Catalyzed by RuCp* Complexes: A Mechanistic Study

Atom‐Transfer Radical Addition Reactions Catalyzed by RuCp* Complexes: A Mechanistic Study

Comparative study of the catalytic activity of the complexes Cp*RuCl(PAr3)2 [Ar = -C6H5 and 4-CF3-C6H4] in the ATRP of styrene

Copper‐Catalyzed Synthesis of 1,2‐Disubstituted Cyclopentanes from 1,6‐Dienes by Ring‐Closing Kharasch Addition of Carbon Tetrachloride

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Atom‐Transfer Radical Addition (ATRA) and Cyclization (ATRC) Reactions Catalyzed by a Mixture of [RuCl2Cp*(PPh3)] and Magnesium

Cited by 111 publications

References 77 publications

Atom‐Transfer Radical Addition Reactions Catalyzed by RuCp* Complexes: A Mechanistic Study

Atom‐Transfer Radical Addition Reactions Catalyzed by RuCp* Complexes: A Mechanistic Study

Comparative study of the catalytic activity of the complexes Cp*RuCl(PAr3)2 [Ar = -C6H5 and 4-CF3-C6H4] in the ATRP of styrene

Copper‐Catalyzed Synthesis of 1,2‐Disubstituted Cyclopentanes from 1,6‐Dienes by Ring‐Closing Kharasch Addition of Carbon Tetrachloride

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Atom‐Transfer Radical Addition (ATRA) and Cyclization (ATRC) Reactions Catalyzed by a Mixture of [RuCl₂Cp*(PPh₃)] and Magnesium