Synthesis and Structure of a Mixed-Ligand Dinuclear Ruthenium Trihydrido Complex Supported by Cn* and Cp* Ligands (Cn* = 1,4,7-Trimethyl-1,4,7-triazacyclononane, Cp* = η5-C5Me5): Enhancement of Reactivity toward CO2by Introduction of the Cn* Ligand

Namura, Kyo; Ohashi, Masato; Suzuki, Hiroharu

doi:10.1021/om3004674

Cited by 7 publications

(6 citation statements)

References 38 publications

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“…The proton-coupled 13 C NMR spectrum of 2a recorded at 25 °C exhibits a set of doublet signals characteristic of the μ-formato group at δ 171.1. The shift is also similar to those of the above-mentioned μ-formato complexes. , …”

supporting

confidence: 83%

“…The validity of the notably lower shift of the hydride ligand was demonstrated by gauge-independent atomic orbital (GIAO) calculations (see Supporting Information). A signal for the proton attached to the μ-formato carbon appears at δ 6.80, which is comparable to the chemical shifts observed in the analogous μ-formato complexes Cp*Ru(μ-OCHO) 2 (μ-H) 2 RuCp* (δ 6.75) and Cn*Ru(μ-OCHO) 2 (μ-H)RuCp* (δ 7.85) . The proton-coupled 13 C NMR spectrum of 2a recorded at 25 °C exhibits a set of doublet signals characteristic of the μ-formato group at δ 171.1.…”

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confidence: 60%

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Photochemical Reaction of Diruthenium Tetrahydride-Bridged Complexes with Carbon Dioxide: Insertion of CO₂ into a Ru–H Bond versus C═O Double-Bond Cleavage

et al. 2014

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Photochemical reactions of diruthenium tetrahydride complexes containing cyclopentadienyls as auxiliary ligands with carbon dioxide were studied for the effective fixation and reduction of CO 2 . Whereas the reactions of CpsRu(μ-H) 4 RuCps (Cps = Cp*, C 5 Me 5 ; Cp Et , C 5 Me 4 Et; Cp ‡ , 1,2,4-C 5 ( t Bu) 3 H 2 ) with CO 2 did not proceed under dark and mild conditions, the photochemical reactions under UV (365 nm) irradiation smoothly proceeded to afford two types of products, (i) a μ-formato complex and (ii) a μ-carbonyl-μ-oxo complex, according to the width of the space for the reaction stretching between the two auxiliary cyclopentadienyl ligands.T he photochemical behavior of mononuclear polyhydrido transition metal complexes has been intensively studied since the early 1970s. 1 Reductive elimination of H 2 is the most salient process observed in the initial stages of photolysis of mononuclear polyhydride species. 2 The coordinatively unsaturated, highly reactive species generated by dehydrogenation often promote bond activation of relatively inert hydrocarbons. 3 In contrast, polynuclear polyhydride-bridged complexes tend to be highly resistant toward reductive elimination of H 2 , because each hydride ligand is bound to multiple metal centers. 4 Initial reactions observed for the photolysis of mononuclear polyhydride complexes, i.e., the formation of vacant sites via liberation of H 2 , would, therefore, be impeded upon photoexcitation of a bridging polyhydride cluster. At the same time, preservation of the bridging hydrides would prevent fragmentation of the cluster framework.Recently, we reported photoinduced C−H bond cleavage of acetone, resulting in the formation of a dinuclear bridging oxatrimethylenemethane complex of ruthenium. 5 This reaction is considered to be very typical of polyhydride-bridged cluster complexes, because the reaction mechanism does not involve either initial H 2 elimination or fragmentation of the cluster framework. This result strongly stimulated us to examine the reaction of the polyhydride-bridged clusters with carbon dioxide under photoirradiation to activate less-reactive CO 2 in a bimetallic way.Carbon dioxide has long been considered to be an abundantly available feedstock for C 1 chemistry as well as carbon monoxide, methanol, and methane. 6 However, the chemical inertness of CO 2 , originating from its highly negative reduction potential, has limited its use in organic transformations. Consequently, activation of CO 2 via coordination to a transition metal has become a subject of great interest. 7 Coordination patterns are primarily controlled by the electronic situation at the metal center, and thus, electron-rich transition metal centers can perform a nucleophilic attack at the carbon atom of CO 2 . 8 In contrast, electron-poor metal centers act as electrophiles and react with CO 2 via one of the oxygen atoms. 9 We report herein that the reactions of CpsRu(μ-H) 4 RuCps with CO 2 smoothly proceed with preservation of dinuclear structure under UV irradiation to pro...

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supporting

confidence: 83%

supporting

confidence: 60%

Photochemical Reaction of Diruthenium Tetrahydride-Bridged Complexes with Carbon Dioxide: Insertion of CO₂ into a Ru–H Bond versus C═O Double-Bond Cleavage

et al. 2014

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“…The electron density at the ruthenium atom bonded to the Cn* ligand should be markedly increased due to the strong σ-donor character of the Cn* ligand. As expected, the mixed-ligand complex Cn*Ru(μ-H) 3 RuCp* smoothly reacted with CO 2 to afford a di-μ-formato complex, Cn*Ru(μ-η 1 :η 1 -O 2 CH) 2 (μ-H)RuCp* ( 8 ), whereas the reaction of pressurized CO 2 with a homoligand dinuclear complex, Cp*Ru(μ-H) 4 RuCp*, was hampered owing to a lack in nucleophilicity of the Ru centers. We synthesized a new type of mixed-ligand complex containing Cn* and bulky phosphine ligands.…”

Section: Resultssupporting

confidence: 57%

“…The Ru1–Ru2 distances of 3a – c were 2.4757(5), 2.4761(6), and 2.4785(3) Å, respectively, and they were hardly affected by variations in phosphine ligands. These values were comparable to the Ru–Ru distances of a 30e diruthenium trihydrido complex with hexamethylbenzene ligands, [{(η 6 -C 6 Me 6 )Ru} 2 (μ-H) 3 ](PF 6 ) (2.4681(4) Å), and a diruthenium trihydrido complex with Cn* and Cp* ligands, Cn*Ru(μ-H) 3 RuCp* (2.4676(6) Å) . On the other hand, there were small differences in the P1–Ru2–P2 angles among 3a (115.83(4)°), 3b (114.79(5)°), and 3c (111.67(3)°) that are likely due to the bulkiness of the phosphine ligands.…”

Section: Resultssupporting

confidence: 55%

“…In addition to metallic combinations, mixed ligands may also serve to originate anisotropy in the reaction sites of the cluster. We recently synthesized a diruthenium complex supported by 1,4,7-trimethyl-1,4,7-triazacyclononane (Cn*) and Cp* ligands, Cn*Ru(μ-H) 3 RuCp*, and examined the influence of these ligands on the structure, electronic properties, and reactivity of the complex . In this context, we synthesized several diruthenium polyhydrido complexes that were supported by Cn* and some bulky phosphine ligands as a new series of homometallic mixed-ligand polyhydrido clusters.…”

Section: Introductionmentioning

confidence: 99%

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Synthesis, Structure, and Reactivity of Mixed-Ligand Dinuclear Ruthenium Polyhydrido Complexes Supported by 1,4,7-Trimethyl-1,4,7-triazacyclononane and Bulky Phosphine Ligands

Namura

Suzuki

2014

Organometallics

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To construct electronically and sterically anisotropic reaction sites of dinuclear cluster, mixed-ligand diruthenium pentahydrido complexes [Cn*Ru(μ-H) 3 Ru-(H) 2 (PR 3 ) 2 ] + (Cn* = 1,4,7-trimethyl-1,4,7-triazacyclononane; R = Cy (3a), i Pr (3b), cyclopentyl (Cyp, 3c)) were synthesized by the reaction of [Cn*RuH(H 2 ) 2 ] + (1) with Ru-(H) 2 (H 2 ) 2 (PR 3 ) 2 (R = Cy (2a) i Pr (2b), Cyp (2c)). The treatment of 3a−c with KH afforded the corresponding neutral tetrahydrido complexes Cn*Ru(μ-H) 3 RuH(PR 3 ) 2 (R = Cy (4a), i Pr (4b), Cyp (4c)). The structures of 3 and 4 were confirmed by X-ray diffraction studies. Introduction of the Cn* ligand into the cluster increased the electron density at the Cn*ligated metal center and significantly stimulated reactivitiy toward molecular nitrogen and carbon dioxide. Complexes 3a−c reacted with molecular nitrogen to produce the terminal dinitrogen complexes [Cn*Ru(N 2 )(μ-H) 2 RuH(PR 3 ) 2 ] + (R = Cy (5a), i Pr (5b), Cyp (5c)), which readily underwent dimerization to form the bridging dinitrogen complexes [(μ-N 2 ){RuCn*(μ-H) 2 RuH(PR 3 ) 2 } 2 ] 2+ (R = i Pr (6b), Cyp (6c)), through the liberation of N 2 . Cationic complexes 3a−c reacted with CO 2 to produce the bridging formato complexes [Cn*Ru(μη 1 :η 1 -O 2 CH)(μ-H) 2 Ru(H 2 )(PR 3 ) 2 ] + (R = Cy (7a), i Pr (7b), Cyp (7c)), whereas neutral 4a−c reacted with CO 2 to form the carbonyl complexes [Cn*Ru(CO)(μ-H) 2 RuH(PR 3 ) 2 ] + (R = Cy (9a), i Pr (9b), Cyp (9c)), via cleavage of the CO bond.

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Versatile and highly efficient synthesis of diruthenium tetrahydride complex

Shimogawa

Takao

Suzuki

2016

Journal of Organometallic Chemistry

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Synthesis and Structure of a Mixed-Ligand Dinuclear Ruthenium Trihydrido Complex Supported by Cn* and Cp* Ligands (Cn* = 1,4,7-Trimethyl-1,4,7-triazacyclononane, Cp* = η⁵-C₅Me₅): Enhancement of Reactivity toward CO₂by Introduction of the Cn* Ligand

Cited by 7 publications

References 38 publications

Photochemical Reaction of Diruthenium Tetrahydride-Bridged Complexes with Carbon Dioxide: Insertion of CO₂ into a Ru–H Bond versus C═O Double-Bond Cleavage

Photochemical Reaction of Diruthenium Tetrahydride-Bridged Complexes with Carbon Dioxide: Insertion of CO₂ into a Ru–H Bond versus C═O Double-Bond Cleavage

Synthesis, Structure, and Reactivity of Mixed-Ligand Dinuclear Ruthenium Polyhydrido Complexes Supported by 1,4,7-Trimethyl-1,4,7-triazacyclononane and Bulky Phosphine Ligands

Versatile and highly efficient synthesis of diruthenium tetrahydride complex

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Synthesis and Structure of a Mixed-Ligand Dinuclear Ruthenium Trihydrido Complex Supported by Cn* and Cp* Ligands (Cn* = 1,4,7-Trimethyl-1,4,7-triazacyclononane, Cp* = η5-C5Me5): Enhancement of Reactivity toward CO2by Introduction of the Cn* Ligand

Cited by 7 publications

References 38 publications

Photochemical Reaction of Diruthenium Tetrahydride-Bridged Complexes with Carbon Dioxide: Insertion of CO2 into a Ru–H Bond versus C═O Double-Bond Cleavage

Photochemical Reaction of Diruthenium Tetrahydride-Bridged Complexes with Carbon Dioxide: Insertion of CO2 into a Ru–H Bond versus C═O Double-Bond Cleavage

Synthesis, Structure, and Reactivity of Mixed-Ligand Dinuclear Ruthenium Polyhydrido Complexes Supported by 1,4,7-Trimethyl-1,4,7-triazacyclononane and Bulky Phosphine Ligands

Versatile and highly efficient synthesis of diruthenium tetrahydride complex

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Synthesis and Structure of a Mixed-Ligand Dinuclear Ruthenium Trihydrido Complex Supported by Cn* and Cp* Ligands (Cn* = 1,4,7-Trimethyl-1,4,7-triazacyclononane, Cp* = η⁵-C₅Me₅): Enhancement of Reactivity toward CO₂by Introduction of the Cn* Ligand

Photochemical Reaction of Diruthenium Tetrahydride-Bridged Complexes with Carbon Dioxide: Insertion of CO₂ into a Ru–H Bond versus C═O Double-Bond Cleavage

Photochemical Reaction of Diruthenium Tetrahydride-Bridged Complexes with Carbon Dioxide: Insertion of CO₂ into a Ru–H Bond versus C═O Double-Bond Cleavage