The Chemical and Catalytic Reactions of Dichlorotris(Triphenylphosphine)Ruthenium(II) and its Major Derivatives

Jardine, F. H.

doi:10.1002/9780470166321.ch4

Cited by 63 publications

(3 citation statements)

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“…Ruthenium(II) complexes containing both nitrogen and phosphino ligands are well-known since the pioneering works of Wilkinson on RuCl 2 (PPh 3 ) 3 , and the research in this area has led to the synthesis of a large number of derivatives with different combinations of P and N donor ligands . The interest in this type of complexes has strongly increased in the last decade following the discovery by Noyori and co-workers that trans -RuCl 2 (PP)(1,2-diamine) (PP = diphosphine) containing chiral phosphine and amine ligands can promote the rapid and highly stereoselective hydrogenation of ketones, and evidence has been provided that the Ru−H/−NH 2 motif is crucial for the activity of these catalysts .…”

Section: Introductionmentioning

confidence: 99%

2-(Aminomethyl)pyridine−Phosphine Ruthenium(II) Complexes: Novel Highly Active Transfer Hydrogenation Catalysts

et al. 2005

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The complexes trans,cis-RuCl2(PPh3)2(ampy) (1) and trans-RuCl2[Ph2P(CH2)4PPh2](ampy) (2) have been prepared in high yield by reaction of RuCl2(PPh3)3 and RuCl2(PPh3)[Ph2P(CH2)4PPh2] with 2-(aminomethyl)pyridine (ampy) at room temperature by PPh3 displacement. Heating compound 1 in refluxing toluene leads to the isomer cis,cis-RuCl2(PPh3)2(ampy) (3), which has been proven to be a good precursor for the preparation of the complexes cis-RuCl2(PP)(ampy) [PP = (S,S)-Chiraphos, 4; Ph2P(CH2)3PPh2, 5; (S,S)-Skewphos, 6; Ph2P(CH2)4PPh2, 7; (R,R)-Diop, 8] by displacement of two PPh3 with the appropriate diphosphine. The derivatives cis-RuCl2(PP)(ampy) [PP = (R,S)-Josiphos, 9; (R,S)-tBu-Josiphos, 10] have been synthesized from RuCl2(PPh3)3 and PP followed by addition of ampy. The chiral complexes 4, 6, 8, 9, and 10 are formed stereoselectively, as inferred by NMR data in solution. For the derivatives 7 and 9 the molecular structures have been determined by X-ray measurements. The monohydride complex trans,cis-RuHCl(PPh3)2(ampy) (11) has been prepared from RuHCl(PPh3)3 and ampy in heptane by PPh3 substitution. Compound 11 reacts with sodium isopropoxide in toluene, affording the dihydride derivative cis,trans-Ru(H)2(PPh3)2(ampy) (12) via the alkoxide route. The intermediate species cis,cis-Ru(H)2(PPh3)2(ampy) (A) has been also characterized by NMR in solution. All these complexes have been found to be highly efficient transfer hydrogenation catalysts. With the complexes cis-RuCl2(PP)(ampy) a large number of ketones (dialkyl, diaryl, and alkyl-aryl) can be quantitatively reduced to alcohols in 2-propanol and in the presence of NaOH (ketone/Ru/NaOH = 2000/1/40) with remarkably high TOF values (up to 400 000 h-1 at 50% conversion). The derivatives containing chiral diphosphines afforded rapid (TOF > 105 h-1) and enantioselective (ee up to 94%) reduction of methyl-aryl ketones using low loading of catalysts (0.05−0.01 mol %). In the absence of base the dihydride compound 12 catalyzes the transfer hydrogenation of acetophenone.

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Section: Introductionmentioning

confidence: 99%

2-(Aminomethyl)pyridine−Phosphine Ruthenium(II) Complexes: Novel Highly Active Transfer Hydrogenation Catalysts

et al. 2005

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“…The distortion is also reflected by the P(1)–Ru(1)–P(2) angle of 97.37(2)° and the significantly elongated Ru(1)–P(2) bond of 2.3925(7) Å compared to the Ru(1)–P(1) bond of 2.3090(7) Å. With a value of 2.4098(6) Å, the Ru(1)–Cl(1) bond length suggests the ruthenium(II) oxidation state . The intramolecular Ru–Ru distance of 6.7153(5) Å in combination with the planar μ-LH 2 ligand should enable an intramolecular electron transfer.…”

Section: Resultsmentioning

confidence: 99%

Redox Behavior of a Dinuclear Ruthenium(II) Complex Bearing an Uncommon Bridging Ligand: Insights from High-Pressure Electrochemistry

Dürr¹,

Klein

Kahnt³

et al. 2017

Inorg. Chem.

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A dinuclear ruthenium complex bridged by 2,3,5,6-pyrazinetetracarboxylic acid (μ-LH) was synthesized and characterized by X-ray crystallography, cyclic voltammetry under ambient and elevated pressures, electron paramagnetic resonance (EPR) and UV/vis-NIR (NIR = near-infrared) spectroelectrochemistry, pulse radiolysis, and computational methods. We probed for the first time in the field of mixed-valency the use of high-pressure electrochemical methods. The investigations were directed toward the influence of the protonation state of the bridging ligand on the electronic communication between the ruthenium ions, since such behavior is interesting in terms of modulating redox chemistry by pH. Starting from the [Ru(μ-LH)Ru] configuration, which shows an intense metal-to-ligand charge transfer absorption band at 600 nm, cyclic voltammetry revealed a pH-independent, reversible one-electron reduction and a protonation-state-dependent (proton coupled electron transfer, PCET) reversible oxidation. Deeper insight into the electrode reactions was provided by pressure-dependent cyclic voltammetry up to 150 MPa, providing insight into the conformational changes, the protonation state, and the environment of the molecule during the redox processes. Spectroelectrochemical investigations (EPR, UV/vis-NIR) of the respective redox reactions suggest a ligand-centered radical anion [Ru(μ-LH)Ru] upon reduction (EPR Δg = 0.042) and an ambiguous, EPR-silent one-electron oxidized state. In both cases, the absence of the otherwise typical broad intervalence charge transfer bands in the NIR region for mixed-valent complexes support the formulation as radical anionic bridged compound. However, on the basis of high-pressure electrochemical data and density functional theory calculations the one-electron oxidized form could be assigned as a charge-delocalized [Ru(μ-LH)Ru] valence tautomer rather than [Ru(μ-LH)Ru]. Deprotonation of the bridging ligand causes a severe shift of the redox potential for the metal-based oxidation toward lower potentials, yielding the charge-localized [Ru(μ-LH)Ru] complex. This PCET process is accompanied by large intrinsic volume changes. All findings are supported by computational methods (geometry optimization, spin population analysis). For all redox processes, valence alternatives are discussed.

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“…Neutral ruthenium(II) chloro complexes with monodentate phosphine ligands are key starting materials in organometallic synthesis , and catalysis. , With small phosphine ligands such as PMe 3 , PMe 2 (CH 2 Ph), and PMe 2 Ph, electronically saturated complexes of the formula [RuCl 2 L 4 ] (L = PR 3 , PR 2 R‘) ( A ) can be obtained (Scheme ). The 16-electron complexes [RuCl 2 L 3 ] ( C ) are formed with sterically more demanding ligands such as PPh 3 , P( p -C 6 H 4 CH 3 ) 3 , and PEtPh 2 . In solution, complexes with the latter ligand are in equilibrium with the dimer [Ru 2 Cl 4 (PEtPh 2 ) 5 ] ( B ) .…”

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confidence: 99%

Syntheses and Structures of the Trinuclear Ruthenium Complexes [RuCl₂(PAd₂Bu)]₃and [RuCl₂(P^tBu₂Cy)]₃

2005

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The Chemical and Catalytic Reactions of Dichlorotris(Triphenylphosphine)Ruthenium(II) and its Major Derivatives

Cited by 63 publications

References 298 publications

2-(Aminomethyl)pyridine−Phosphine Ruthenium(II) Complexes: Novel Highly Active Transfer Hydrogenation Catalysts

2-(Aminomethyl)pyridine−Phosphine Ruthenium(II) Complexes: Novel Highly Active Transfer Hydrogenation Catalysts

Redox Behavior of a Dinuclear Ruthenium(II) Complex Bearing an Uncommon Bridging Ligand: Insights from High-Pressure Electrochemistry

Syntheses and Structures of the Trinuclear Ruthenium Complexes [RuCl₂(PAd₂Bu)]₃and [RuCl₂(P^tBu₂Cy)]₃

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The Chemical and Catalytic Reactions of Dichlorotris(Triphenylphosphine)Ruthenium(II) and its Major Derivatives

Cited by 63 publications

References 298 publications

2-(Aminomethyl)pyridine−Phosphine Ruthenium(II) Complexes: Novel Highly Active Transfer Hydrogenation Catalysts

2-(Aminomethyl)pyridine−Phosphine Ruthenium(II) Complexes: Novel Highly Active Transfer Hydrogenation Catalysts

Redox Behavior of a Dinuclear Ruthenium(II) Complex Bearing an Uncommon Bridging Ligand: Insights from High-Pressure Electrochemistry

Syntheses and Structures of the Trinuclear Ruthenium Complexes [RuCl2(PAd2Bu)]3and [RuCl2(PtBu2Cy)]3

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Syntheses and Structures of the Trinuclear Ruthenium Complexes [RuCl₂(PAd₂Bu)]₃and [RuCl₂(P^tBu₂Cy)]₃