- Exceedingly Facile Ph-X Activation (X=Cl, Br, I) with Ruthenium(II): Arresting Kinetics, Autocatalysis, and Mechanisms
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[(Ph3P)3Ru(L)(H)2] (where L=H2 (1) in the presence of styrene, Ph3P (3), and N2 (4)) cleave the Ph-X bond (X=Cl, Br, I) at RT to give [(Ph3P)3RuH(X)] (2) and PhH. A combined experimental and DFT study points to [(Ph3P)3Ru(H)2] as the reactive species generated upon spontaneous loss of L from 3 and 4. The reaction of 3 with excess PhI displays striking kinetics which initially appears zeroth order in Ru. However mechanistic studies reveal that this is due to autocatalysis comprising two factors: 1) complex 2, originating from the initial PhI activation with 3, is roughly as reactive toward PhI as 3 itself; and 2) the Ph-I bond cleavage with the just-produced 2 gives rise to [(Ph3P)2RuI2], which quickly comproportionates with the still-present 3 to recover 2. Both the initial and onward activation reactions involve PPh3 dissociation, PhI coordination to Ru through I, rearrangement to a η2-PhI intermediate, and Ph-I oxidative addition.
- Miloserdov, Fedor M.,McKay, David,Mu?oz, Bianca K.,Samouei, Hamidreza,MacGregor, Stuart A.,Grushin, Vladimir V.
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p. 8466 - 8470
(2015/11/27)
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- Solid-State structure and solution reactivity of [(Ph3P)4Ru(H)2] and related Ru(II) complexes used in catalysis: A reinvestigation
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X-ray analysis of [(Ph3P)4Ru(H)2] (1) prepared by a literature procedure [ Young, R.; Wilkinson, G. Inorg. Synth. 1990, 28, 337 ] shows that 1 is cocrystallized with PPh3, explaining the previously reported observations of free phosphine in solutions of 1. Lattice PPh3-free forms of 1 have also been obtained, structurally characterized, and found to generate small quantities of uncoordinated PPh3 and another species (A) in solution. Against previous beliefs, however, A is not [(Ph3P)3Ru(H)2] (2), but [(Ph3P)3Ru(H2)(H)2] (3) that forms in the reaction of 1 with adventitious water. This reaction apparently occurs via PPh3 loss from 1 to give 2, followed by H2O coordination, Ru(H)(OH2)/Ru(H2)(OH) rearrangement, H2 loss, and dimerization to give [(Ph3P)4Ru2(H)2(μ-OH)2] (4). The H2 thus produced is trapped with 2 to give 3. Complexes 3·0.5C6H6, 3·2THF, 4·2H2O, [(Ph3P)3Ru(N2)(H)2] (5), and [(Ph3P)2(H)Ru(μ-H)3Ru(PPh3)3]·0.5THF (6·0.5THF) have been structurally characterized for the first time. Also for the first time, a single-crystal X-ray diffraction study of the long-known [(Ph3P)4RuCl2] (7) has been performed to finally demonstrate that 7 is, in fact, [(Ph3P)3RuCl2]·PPh3, precisely as proposed by Hoffman and Caulton as early as 1975 [ Hoffman, P.R.; Caulton, K.G. J. Am. Chem. Soc. 1975, 97, 4221 ].
- Samouei, Hamidreza,Miloserdov, Fedor M.,Escudero-Adn, Eduardo C.,Grushin, Vladimir V.
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p. 7279 - 7283
(2015/09/08)
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- C-C bond formation via C-H bond activation using an in situ-generated ruthenium catalyst
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We report here our full results concerning the possibility of generatingin situ from a stable and readily available ruthenium(II) source a high ly active ruthenium catalyst for C-H bond activation. The versatility ofthis catalytic system has been demonstrated, as it offers the possibili ty of modifying the electronic and steric properties of the catalyst by fine-tuning of the ligands, allowing functionalization of various substrates. Aromatic ketones and imines could be easily functionalized by the reaction with either vinylsilanes or styrenes, depending on the electronic and steric nature of the ligand. Moreover, variable-temperature NMR experiments and the isolation of a ruthenium intermediate complex provided some insights into the generation of the active catalytic ruthenium species in this reaction.
- Martinez, Remi,Simon, Marc-Olivier,Chevalier, Reynald,Pautigny, Cyrielle,Genet, Jean-Pierre,Darses, Sylvain
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p. 7887 - 7895
(2009/10/17)
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- Michael reaction of stabilized carbon nucleophiles catalyzed by [RuH2(PPh3)4]
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The Michael reaction of active methylene compounds lacking cyano groups such as malonates, β-ketoesters, 1,3-diketones, 1,1-disulfones, nitrocompounds, Meldrum acid, and anthrone with common acceptors proceeds in acetonitrile solution in the presence of [RuH2(PPh3)4] as the catalyst. Cyano acetates, more acidic than malonates in organic solvents, are also excellent substrates for this reaction. In a number of cases, intramolecular aldol reactions catalyzed by [RuH2(PPh3)4] were also observed as side reactions. Catalysis by other ruthenium and rhodium complexes has been examined. Selectivity studies performed with malonate and disulfone donors indicate that the catalyst selectively activates Michael donors that can coordinate with ruthenium(II). Additionally, it has been shown that the reaction requires the presence of free phosphine. Therefore, the Michael reaction of stabilized enolates appears to be a ruthenium- and phosphine-catalyzed reaction. From a practical point of view, the use of readily prepared [RuH2(PPh3)4] as the catalyst in acetonitrile provided the best solution for the Michael reaction of active methylene compounds.
- Gómez-Bengoa, Enrique,Cuerva, Juan M.,Mateo, Cristina,Echavarren, Antonio M.
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p. 8553 - 8565
(2007/10/03)
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- Roles of Neutral and Anionic Ruthenium Polyhydrides in the Catalytic Hydrogenation of Ketones and Arenes
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fac-- (1) and (3) have been shown to coexist through the equilibrium 1 + ROH 3 + RO-, for which Keq ca. 0.13 for cyclohexanol in THF.The following reactions have been characterized: (1) 3 +
- Linn, Donald E.,Halpern, Jack
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p. 2969 - 2974
(2007/10/02)
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- New Synthesis and Molecular Structure of Potassium Trihydridotris(triphenylphosphine)ruthenate
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A convenient, high yield method for the synthesis of ruthenium hydrides, including anionic ruthenium hydrides, has been developed; the molecular structure of potassium trihydridotris(triphenylphosphine)ruthenate (2) complexed with 18-crown-6-ether has been determined by single crystal X-ray diffraction.
- Chan, Albert S. C.,Shieh, Huey-Sheng
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p. 1379 - 1380
(2007/10/02)
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- PREPARATION AND PROPERTIES OF GROUP 8 TRANSITION METAL ALKOXIDES RELEVANT TO CATALYTIC HYDROGENATION OF KETONES TO ALCOHOLS
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Alkoxo complexes, M(OR)Ln and MH(OR)Ln (M=Co, Rh, Ru, L=PPh3; R=CH(CF3)2, CHPh(CF3)), have been prepared by insertion of fluoroketones into M-H bonds in CoH(N2)L3, RhHL4, and RuH2L4.Hydrogenolysis of the Ru- and Rh-alkoxo complexes w
- Hayashi, Yoshinori,Komiya, Sanshiro,Yamamoto, Takakazu,Yamamoto, Akio
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p. 1363 - 1366
(2007/10/02)
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