- Construction of a visible light-driven hydrocarboxylation cycle of alkenes by the combined use of Rh(i) and photoredox catalysts
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A visible light driven catalytic cycle for hydrocarboxylation of alkenes with CO2 was established using a combination of a Rh(i) complex as a carboxylation catalyst and [Ru(bpy)3]2+ (bpy = 2,2′- bipyridyl) as a photoredox catalyst. Two key steps, the generation of Rh(i) hydride species and nucleophilic addition of π-benzyl Rh(i) species to CO2, were found to be mediated by light.
- Murata, Kei,Numasawa, Nobutsugu,Shimomaki, Katsuya,Takaya, Jun,Iwasawa, Nobuharu
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supporting information
p. 3098 - 3101
(2017/03/17)
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- Diverting Hydrogenations with Wilkinson's Catalyst towards Highly Reactive Rhodium(I) Species
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The addition of Barton's base has a dramatic effect on the classic rhodium(III)-mediated hydrogenations promoted by Wilkinson′s catalyst. Following the initial oxidative addition, a barrierless reductive elimination of HCl from the traditional rhodium(III) intermediates instantly produces a rhodium(I) monohydride species, which is remarkably reactive in the hydrogenation of several internal alkynes and functionalized trisubstituted alkenes. The direct formation of this species is unprecedented upon addition of molecular hydrogen and its catalytic potential has been hitherto barely explored.
- Perea-Buceta, Jesus E.,Fernández, Israel,Heikkinen, Sami,Axenov, Kirill,King, Alistair W. T.,Niemi, Teemu,Nieger, Martin,Leskel?, Markku,Repo, Timo
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supporting information
p. 14321 - 14325
(2016/01/25)
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- Using NMR and ESI-MS to probe the mechanism of silane dehydrocoupling catalyzed by wilkinson's catalyst
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The reaction of Wilkinson's catalyst Rh(PPh3)3Cl (1) with 1-2 equiv. of di-n-hexylsilane gives rise to a complex mixture of products, which has been analyzed by 31P{1H} NMR and shown to include the hydrido complex Rh(PPh3)3H (3). Continuous sampling of the 1:1 reaction mixture by ESI-MS provided time-dependent speciation that tracks the formation of 3 at the expense of the initial silane oxidative addition product [Rh(PPh3)2(Cl)(H){Si(nHex) 2H}] (2), the subsequent 1st order disappearance of 3, and the formation of other, minor side-products. Our results provide insight into established activity of 1 for catalytic dehydrocoupling of di-n-hexylsilane, and implicate complex 3 as the active species in this catalysis. The combination of 31P NMR and ESI-MS provides detailed insight into the dynamics of the activation of a secondary silaneby Rh(PPh3)3Cl, with strong evidence pointing to the role of Rh(PPh3)3H as the active catalyst for silane dehydrocoupling and to the deleterious effect of trace water in this system. Copyright
- Jackson, Sarah M.,Chisholm, Danielle M.,McIndoe, J. Scott,Rosenberg, Lisa
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p. 327 - 330
(2011/05/07)
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- Phosphinorhodium-catalyzed dehalogenation of chlorinated and fluorinated ethylenes: Distinct mechanisms with triethylsilane and dihydrogen
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Catalytic dehalogenation of chlorinated and fluorinated ethylenes by (PR3)3RhCl complexes is described. The C-Cl and C-F bonds are activated by the catalyst in the presence of triethylsilane (Et 3SiH) or dihydrogen (H
- Peterson, Alicia A.,Thoreson, Kristen A.,McNeill, Kristopher
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p. 5982 - 5991
(2010/02/16)
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- Dehalogenation of hexachlorocyclohexanes and simultaneous chlorination of triethylsilane catalyzed by rhodium and ruthenium complexes
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Complexes RhCl(PPh3)3 and RhH2Cl(P iPr3)2 catalyze the dehalogenation of γ-hexachloro-cyclohexane to benzene and the simultaneous chlorination of HSiEt3 to ClSiEt3. In
- Esteruelas, Miguel A.,Herrero, Juana,Olivan, Montserrat
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p. 3891 - 3897
(2008/10/09)
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- Reactions of catecholborane with wilkinson's catalyst: Implications for transition metal-catalyzed hydroborations of alkenes
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Reactions of catecholborane (HBO2C6H4) with RhCl(PPh3)3 (1) yield a variety of products depending on the B/Rh ratio, solvent, and temperature. Of particular relevance to catalyzed alkene hydroboration is degradation of HBO2C6H4 to B2(O2C6H4)3/'BH 3' and the dihydride RhH2Cl(PPh3)3 (3). The molecular structure of 3, determined by X-ray diffraction, has meridional phosphine ligands and cis hydrides. Catalyst systems formed from in situ addition of PPh3 to [Rh(μ-Cl)(COD)]2 (COD = 1,5-cyclooctadiene) are fundamentally different from Wilkinson's catalyst; RhCl(COD)(PPh3) forms initially, but the reaction of this with PPh3 is slow. Monitoring catalyzed hydroborations using Wilkinson's catalyst and catecholborane by multinuclear NMR spectroscopy, prior to oxidative workup, showed that alkylboranes were formed with some sterically hindered alkenes. With 2-methylbut-2-ene (24), for example, we observed significant quantities of disiamylborane, (CHMeCHMe2)2, formed via addition of 'BH3' to 24. When excess PPh3 was added to the catalyst system, however, the desired alkylboronate ester was formed in high yield. Partial oxidation of RhCl(PPh3)3 had a significant effect on product (and D-label) distributions. Detailed investigations of catalyzed additions of DBO2C6H4 to allylic silyl ethers CH2=C(Me)CRR′(OSitBuMe2) (R, R′ = H, Me) demonstrated that deuterium incorporation at the carbon bonded to boron in the primary alcohol product occurs only with freshly prepared Wilkinson's catalyst or when excess PPh3 is added to the oxidized catalyst. With freshly prepared Wilkinson's catalyst, addition of H2 (or D2) to these substrates is a significant competing reaction and appreciable catalytic formation of vinylboronate esters is also observed. The latter presumably arise via insertion of alkene into a Rh-B bond, followed by β-hydride elimination. Subsequent in situ addition of H2 (DH or D2) to these vinylboronate esters provides an alternative explanation to α-deuterium incorporation into the resulting primary alcohols.
- Burgess, Kevin,Van Der Donk, Wilfred A.,Westcott, Stephen A.,Marder, Todd B.,Baker, R. Thomas,Calabrese, Joseph C.
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p. 9350 - 9359
(2007/10/02)
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- The reaction of with thiols: a 1H and 31P NMR study
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In toluene or THF at -40 deg C (RhH(PPh3)4> reacts with RSH (R = Pri, Ph, CH2Ph) to give the unstable dihydro complex .At 20 deg C decomposition of this complex with loss of H2 occurs via a five-coordinate species RhH2(SR)(PPh
- Carlton, Laurence,Bulbulia, Zaid
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p. 139 - 147
(2007/10/02)
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- Untersuchungen zum Mechanismus der Rhodium(I)-katalysierten Hydrogen-Transfer-Reaktion von sekundaeren Alkoholen auf Imine
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The results of a series of systematically performed experiments form the basis for a model that elucidates the catalytic cycle of the hydrogen transfer reaction from 2-propanol to imines forming secondary amines in the presence of Wilkinson's catalyst.
- Brune, Hans-Albert,Unsin, Josef,Hemmer, Reinhard,Reichhardt, Monika
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p. 335 - 342
(2007/10/02)
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- Preparation, x-ray molecular structure determination, and chemical properties of dinitrogen-coordinated cobalt complexes containing triphenylphosphine ligands and alkali metal or magnesium. Protonation of the coordinated dinitrogen to ammonia and hydrazine
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Treatment of CoH(N2)(PPh3)3 (1) with diethylmagnesium gave a magnesium-containing complex 2 formulated as [Co(N2)(PPh3)3]2Mg(THF)4 (THF = tetrahydrofuran). Subsequent reaction of 2 or direct reaction of 1 with LiBu afforded Li-containing complexes [Co(N2)(PPh3)3]Li(Et2O)3 (3) and [Co(N2)-(PPh3)3]Li(THF)3 (4) depending on the solvent employed. A Na-containing complex, [Co(N2)(PPh3)3]-Na(THF)3 (5), was also obtained by the reaction of 1 with sodium metal. The molecular structures of 3 and 4 were fully established by X-ray structural analysis. These complexes are isomorphous and have a threefold symmetry with the N2 ligand bridging Co and Li on its both ends with the N-N bond length of 1.167 (16) ? for 3 and 1.19 (4) ? for 4. In contrast to 1 whose coordinated N2 ligand is incapable of reacting with protic acids, the ligated N2 in the electron-rich cobalt complexes 2-5 is attacked by concentrated H2SO4 to afford hydrazine and ammonia. These complexes provide the first examples of the conversion of dinitrogen coordinated to cobalt into hydrazine and ammonia on hydrolysis. The corresponding iron analogue having a ligating dinitrogen also was prepared by the reaction of Fe(acac)3 with MgEt2 in the presence of 2-6 equiv of PPh3 under nitrogen. The complex was characterized as [FeEt(N2)-(PPh3)2]2Mg(THF) 4 (6). Complex 6 also affords hydrazine and ammonia on acidolysis.
- Yamamoto, Akio,Miura, Yoshikiyo,Ito, Takashi,Chen, Hui-Lin,Iri, Kiyoshi,Ozawa, Fumiyuki,Miki, Kunio,Sei, Tsuyoshi,Tanaka, Nobuo,Kasai, Nobutami
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p. 1429 - 1436
(2008/10/08)
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