Synthesis and Properties of Diruthenium Tetrahydrides Supported by Less-substituted, Sterically Demanding Poly-<i>tert</i>-butylated Cyclopentadienyls

Yanagi, Taketoshi; Suzuki, Hiroharu

doi:10.1246/cl.130699

Cited by 11 publications

(10 citation statements)

References 35 publications

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“…[5,6] Subsequent research was focused mostly on using different alcohols under moderate hydrogen pressure (1-20 bar). [7][8][9] Toste et al obtained best results with 3-pentanol and 3octanol. [10] Alcohols such as 1-heptanol and cyclohexanol also showed some reactivity for deoxydehydration (DODH) over oxo-rhenium catalysts.…”

Section: Introductionmentioning

confidence: 99%

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H₂‐Free Re‐Based Catalytic Dehydroxylation of Aldaric Acid to Muconic and Adipic Acid Esters

2020

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As one of the most demanded dicarboxylic acids, adipic acid can be directly produced from renewable sources. Hexoses from (hemi)cellulose are oxidized to aldaric acids and subsequently catalytically dehydroxylated. Hitherto performed homogeneously,w ep resent the first heterogeneous catalytic process for converting an aldaric acid into muconic and adipic acid. The contribution of leached Re from the solid prereduced catalyst was also investigated with hot-filtration test and found to be inactive for dehydroxylation. Corrosive or hazardous (HBr/H 2 )reagents are avoided and simple alcohols and solid Re/C catalysts in an inert atmosphere are used. At 120 8 8C, thec arboxylic groups are protected by esterification, which prevents lactonization in the absence of water or acidic sites.Dehydroxylation and partial hydrogenation yield monohexenoates (93 %). Forc omplete hydrogenation to adipate, a1 6% higher activation barrier necessitates higher temperatures.

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Section: Introductionmentioning

confidence: 99%

“…An efficient reductant is PPh 3 (triphenylphosphine) in combination with cyclopentadienyl‐ and tris(pyrazolyl)borate)‐based oxo‐rhenium species [5, 6] . Subsequent research was focused mostly on using different alcohols under moderate hydrogen pressure (1–20 bar) [7–9] . Toste et al.…”

Section: Introductionmentioning

confidence: 99%

H₂‐Free Re‐Based Catalytic Dehydroxylation of Aldaric Acid to Muconic and Adipic Acid Esters

2020

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“…Synthesis of alkyl-appended cyclopentadienyl tricarbonyl rhenium complexes 1a-8a. [46] The recrystallization of 2a and 7a in CH 2 Cl 2 /hexane (2:1) afforded crystals suitable for X-ray diffraction. [23] § Obtained as inseparable mixture.…”

Section: Introductionmentioning

confidence: 99%

Synthesis of Cyclopentadienyl‐Based Tricarbonyl Rhenium Complexes and Some Unusual Reactivities of Cyclopentadienyl Substituents

et al. 2017

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Cyclopentadienyl-based (Cp-based) tricarbonyl rhenium complexes [Cp′Re(CO) 3 ] are convenient precursors for the corresponding Cp-based trioxorhenium complexes (Cp′ReO 3 ), which are potential catalysts for the deoxydehydration (DODH) of diols to olefins. To evaluate the influence of different Cp substituents in Cp′ReO 3 complexes in DODH, a series of alkyl-substituted Cp′Re(CO) 3 complexes (1a-8a) were synthesized. High yields (86-98 %) were obtained from the reactions of Re 2 (CO) 10 with the corresponding Cp′H ligands (1-8). The C-O infrared absorptions of 1a-8a indicate that the electron-donating character of the Cp ligand increases with the number of substituents attached directly to the Cp ring. Analogous aryl-substituted complexes 10a-12a containing bulky phenyl groups were accessed through the salt metathesis of ReBr(CO) 5 with [a] The alkyl-appended Cp′H ligands were either obtained commercially (2, 5, 6, and 8) or synthesized through literature pro-Eur. J. Inorg. Chem. 2017, 741-751 www.eurjic.org 742 Figure 3. Molecular crystal structure of 9a, drawn at the 50 % probability level. Hydrogen atoms are omitted for clarity.Scheme 3. Proposed mechanism for the formation of 9a through the [6+4] cycloaddition of fulvene species B with 1,2,3,4-tetramethylcyclopentadiene 8.

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“…15 In contrast, the bulkiness of the ligands decreases in the order Cp ‡ > Cp Et > Cp*. In the reaction of 1c with CO 2 , dimerization yielding a tetranuclear cluster is completely restrained, while the reaction of 1a and 1b with CO 2 inevitably produces small amounts of the tetranuclear clusters as byproducts.…”

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confidence: 99%

“…We have also demonstrated that two types of reactions proceed with CO 2 under photoirradiation: (i) insertion of CO 2 into a Ru−H bond, affording The electronic properties of the three cyclopentadienyls, Cp*, Cp Et , and Cp ‡ , can be assessed on the basis of the wavenumbers correspond to the stretching vibration of carbonyl group of LRu(CO) 2 Br (L = substituted cyclopentadienyl) as Tolman showed an important relationship between wavenumber ν CO (A 1 mode) of (PR 1 R 2 R 3 )Ni(CO) 3 and the substituent R. 14 Consequently, the electron-donating ability of these ligands was in the order Cp Et > Cp* > Cp ‡ . 15 In contrast, the bulkiness of the ligands decreases in the order Cp ‡ > Cp Et > Cp*. In the reaction of 1c with CO 2 , dimerization yielding a tetranuclear cluster is completely restrained, while the reaction of 1a and 1b with CO 2 inevitably produces small amounts of the tetranuclear clusters as byproducts.…”

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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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Synthesis and Properties of Diruthenium Tetrahydrides Supported by Less-substituted, Sterically Demanding Poly-tert-butylated Cyclopentadienyls

Cited by 11 publications

References 35 publications

H₂‐Free Re‐Based Catalytic Dehydroxylation of Aldaric Acid to Muconic and Adipic Acid Esters

H₂‐Free Re‐Based Catalytic Dehydroxylation of Aldaric Acid to Muconic and Adipic Acid Esters

Synthesis of Cyclopentadienyl‐Based Tricarbonyl Rhenium Complexes and Some Unusual Reactivities of Cyclopentadienyl Substituents

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

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Synthesis and Properties of Diruthenium Tetrahydrides Supported by Less-substituted, Sterically Demanding Poly-tert-butylated Cyclopentadienyls

Cited by 11 publications

References 35 publications

H2‐Free Re‐Based Catalytic Dehydroxylation of Aldaric Acid to Muconic and Adipic Acid Esters

H2‐Free Re‐Based Catalytic Dehydroxylation of Aldaric Acid to Muconic and Adipic Acid Esters

Synthesis of Cyclopentadienyl‐Based Tricarbonyl Rhenium Complexes and Some Unusual Reactivities of Cyclopentadienyl Substituents

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

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H₂‐Free Re‐Based Catalytic Dehydroxylation of Aldaric Acid to Muconic and Adipic Acid Esters

H₂‐Free Re‐Based Catalytic Dehydroxylation of Aldaric Acid to Muconic and Adipic Acid Esters

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