Metallorganische lewissäuren

Heidrich, Jürgen; Loderer, Dirk; Beck, Wolfgang

doi:10.1016/0022-328x(86)80319-9

Cited by 16 publications

(7 citation statements)

References 11 publications

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“…Although [Re(CO) 5 OReO 3 ] was prepared a few years ago by reacting [Re(CO) 5 Br] with AgReO 4 , to our knowledge the coordination of the perrhenate ion to the [Re(CO) 5 ] + moiety was not firmly established up to now . This bonding is easily cleaved by addition of a few drops of 37% aqueous HCl to a solution of [Re(CO) 5 OReO 3 ] in dichloromethane, at room temperature, with formation of [Re(CO) 5 Cl] in quantitative yield.…”

Section: Resultsmentioning

confidence: 99%

“…The silica powder, after extractions as above, is then treated with CH 2 Cl 2 acidified with a few drops of HCl(aq), producing pure [Re(CO) 5 Cl] (43% yield with respect to the initial silica-supported [Re(CO) 3 (OH)] 4 ; Scheme ), which dissolves in CH 2 Cl 2 . Similarly, use of HReO 4 instead of HCl leads to the quantitative conversion of the surface species into [Re(CO) 5 OReO 3 ], which is soluble in dichloromethane (51% yield with respect to the initial silica-supported [Re(CO) 3 (OH)] 4 ; Scheme ). Following the above extraction processes, the combined isolated yields of [Re 2 (CO) 10 ], [Re(CO) 5 X] (X = Cl or OReO 3 ), and unreacted [Re(CO) 3 (OH)] 4 are 88−96%, whereas traces of still unidentified surface rhenium carbonyl species (ν CO as Nujol mull = 2089(w) and 1927(w) cm -1 ) are not extracted even after treatment with CH 2 Cl 2 acidified with HCl(aq).…”

Section: Resultsmentioning

confidence: 99%

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Surface Organometallic Chemistry: Easy Reductive Carbonylation of Silica-Supported [Re(CO)₃(OH)]₄to [Re₂(CO)₁₀] via Silica-Anchored [Re(CO)₅(OSi⋮)] and the Thermal Behavior of Silica-Supported [Re₂(CO)₁₀]

D’Alfonso¹,

Roberto²,

Ugo³

et al. 2000

Organometallics

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Silica-supported [Re(CO) 3 (OH)] 4 is easily converted to [Re 2 (CO) 10 ] by reductive carbonylation under very mild conditions (1 atm CO). This reaction does not occur in solution, suggesting that the silica surface plays a unique role via the surface-anchored species [Re-(CO) 5 (OSit)]. This latter intermediate, of particular interest since organometallic species of the type [Re(CO) 5 (OR)] have so far eluded isolation, reacts with HCl, HReO 4 , and water to give [Re(CO) 5 Cl], [Re(CO) 5 OReO 3 ], and [Re(CO) 3 (OH)] 4 , respectively. No evidence was reached for the previously proposed formation of [HRe 3 (CO) 14 ] in the reductive carbonylation of silica-physisorbed [Re(CO) 3 (OH)] 4 . In addition, silica-supported [Re 2 (CO) 10 ] can be easily reoxidized to [Re(CO) 3 (OH)] 4 on the silica surface by thermal treatment at 150-250 °C under nitrogen. Some highly oxidized rhenium species such as ROReO 3 (R ) H, Sit) are formed in parallel, as suggested by an XPS study and confirmed by further treatment under 1 atm of CO at 200 °C, which affords mixtures containing also [Re(CO) 5 OReO 3 ]. The latter was isolated and fully characterized by X-ray diffraction. Obviously these oxidation reactions, in which the silica surface plays an important positive role, are faster in air than under nitrogen.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Surface Organometallic Chemistry: Easy Reductive Carbonylation of Silica-Supported [Re(CO)₃(OH)]₄to [Re₂(CO)₁₀] via Silica-Anchored [Re(CO)₅(OSi⋮)] and the Thermal Behavior of Silica-Supported [Re₂(CO)₁₀]

D’Alfonso¹,

Roberto²,

Ugo³

et al. 2000

Organometallics

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“…The structures of RReO 3 compounds all show a slightly distorted tetrahedral geometry without “agostic” interactions between C−H and oxygen atoms, and data for some selected complexes is presented in Table . The Re−C bond distances in the σ-coordinated derivatives vary between 200 pm (in PhReO 3 , monoclinic modification) and 208 pm in mesReO 3 and are comparatively short considering the usual range of Re−C single bonds (202−230 pm regardless of the type of carbon hybridization) and Re−C double bonds (187−198 pm). ,,, These short distances seem to result from the strong electron-withdrawing effect of the ReO 3 fragment and the small steric constraint of the Re−C bond in the tetrahedral geometry. In η 5 -Cp‘ReO 3 complexes (Table ) the distance between Re and the centroid of the π-coordinated ring varies between 206 and 208 pm, i.e.…”

Section: Structural and Spectroscopic Characterizationmentioning

confidence: 99%

Rhenium(VII) Oxo and Imido Complexes: Synthesis, Structures, and Applications

1997

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ContentsI. Introduction 3197 II. LReO 3 Compounds and Derivatives 3199 A. Inorganic XReO 3 Compounds and Derivatives 3199 1. Dirhenium Heptaoxide, Re 2 O 7 , and Derivatives 3199 2. Halides and Pseudohalides of Type XReO 3 and Their Adducts 3200 3. R 3 EOReO 3 Compounds and Their Adducts (E ) C, Si, Sn, Ge, Sn, Pb) 3202 4. The Amido R 2 NReO 3 , the Phosphiniminato Complexes, and Their Adducts 3204 5. The Carboxylato Complexes (RCOO)-ReO 3 and Their Adducts 3204 6. The [L 3 ReO 3 ] + and [L 3 ReO 3 ] Complexes 3205 7. Miscellaneous Inorganic LReO 3 Derivatives 3206 8. Structural and Spectroscopic Characterization 3206 9. Reactions of Re 2 O 7 and XReO 3 Compounds 3208 B. Organic RReO 3 Compounds and Derivatives 3209 1. The Alkyl RReO 3 Derivatives 3209 2. The Methyl(vinyl)ReO 3 Complex 3212 3. Allyl, Benzyl, and Pseudoallylic Compounds 3212 4. The Alkinyl RReO 3 Derivatives 3212 5. The Aryl Derivatives 3213 6. The Cyclopentadienyl Derivatives 3213 7. The Indenyl Derivative 3214 8. Structural and Spectroscopic Characterization 3215 9. Reactions of Organic RReO 3 Compounds 3220 10. Applications 3223 III. The L 3 ReO 2 Compounds and Derivatives 3230 A. Inorganic X 3 ReO 2 Derivatives 3230 B. Organic and Mixed Derivatives 3231 IV. The L 4 Re 2 O 5 Compounds and Derivatives 3234 V. The L 5 ReO Compounds and Derivatives 3234 VI. The Re(VII) Imido Compounds and Derivatives 3234 A. The Inorganic XRe(NR) 3 Derivatives 3235 B. The Organic RRe(NR) 3 Derivatives 3236 C. The Inorganic X 3 Re(NR) 2 Derivatives 3236 D. The Organic R 3 Re(NR) 2 Derivatives 3237 E. Miscellaneous Polynuclear and Mixed Imido and Oxo−Imido Derivatives 3238 F. The X 5 Re(NR) Derivatives 3238 G. Reactions of XRe(NR) 3 Complexes 3238 H. Reactions of X 3 Re(NR) 2 and Derivatives 3239 1. The Imido−Alkyne XR(NAr) x (η 2 -C 2 R 2 ) 3-x Complexes 3239 2. The Imido−Alkylidene and Imido−Alkylidyne Complexes 3240 I. Structural Studies 3241 VII. Conclusions 3243 VIII. Abbreviations 3243 IX. Acknowledgments 3243 X. References 3243 3197

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“…The perrhenate anion is a weakly coordinating anion. In comparison to commonly used anions, it is a much weaker base than Cl – but stronger than ClO 4 – , SO 3 CF 3 – , and BF 4 – (basicity: Cl – ≫ ReO 4 – > ClO 4 – > SO 3 CF 3 – ≫ BF 4 – ) . Perrhenates exhibit lower reactivity than structurally analogous permanganates and perchlorates in a variety of reactions.…”

Section: Resultsmentioning

confidence: 99%

“…). 6 Perrhenates exhibit lower reactivity than structurally analogous permanganates and perchlorates in a variety of reactions. On the basis of our previous gas-phase and theoretical studies, 1 substitution or complexation of one oxo moiety on perrhenate to introduce an electron-deficient ligand should render the resultant perrhenate complex metathesis active.…”

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confidence: 99%

Homogeneous Model Complexes for Supported Rhenia Metathesis Catalysts

2012

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A series of rhenium trioxo complexes (L− ReO 3 ) was synthesized, characterized, and demonstrated to be active in olefin metathesis. The relationship between perrhenate (ReO 4 − ), perrhenyl (ReO 3 + ), and metathesis-active rhenium complexes (L−ReO 3 ) was elucidated. Their chemical behavior can be tuned through the Lewis acid−base interaction. DFT calculations were performed for the metathesis reaction of L−ReO 3 with norbornene, which demonstrates that electron-withdrawing substituents or ligands are beneficial for olefin metathesis activity. Moreover, a rhenium− alkylidene complex was synthesized, which can be activated by B(C 6 F 5 ) 3 to afford an active metathesis catalyst. This system can be regarded as a homogeneous model of the hypothetical species present in the heterogeneous catalytic systems. The findings from the present study are consistent with our previous gas-phase studies and constitute the elucidation of the working principles for the metathesis-active rhenium species on the surface. ■ INTRODUCTIONThe system Re 2 O 7 /Al 2 O 3 and its related system, CH 3 ReO 3 (MTO)/Al 2 O 3 −SiO 2 , are effective heterogeneous catalysts for olefin metathesis at ambient temperature, even though the putative rhenium carbene active species is produced only in situ. Understanding of the mechanism on a molecular level for heterogeneous catalysis remains a challenge. Therefore, it is essential to synthesize homogeneous models of the hypothetical surface species present in the rhenium-based heterogeneous catalysts. These models can serve as a bridge between the realms of homogeneous and heterogeneous catalysis and help to elucidate the working principles for those heterogeneous catalysts. Our earlier experimental and computational studies on high-valent rhenium trioxo complexes in the gas phase 1 inspired the pseudo-Wittig mechanism 2 and have proven essential for elucidation of the structural requirements for a self-activating homogeneous metathesis catalyst. As is evident from Scheme 1, a reaction sequence from left to right would provide a route for a rhenium−oxo complex to react with an olefin to form a rhenium carbene by addition, rearrangement, and dissociation. As suggested by qualitative molecular orbital arguments, as well as high-level quantum chemical calculations, 1c this requires that (i) the rhenium center is four-coordinate, (ii) the supporting ligand is a σ-donor, and (iii) the σ-donor ligand is electron-deficient. In other words, the electronic property of L in L−ReO 3 plays an important role in metathesis activity.From a structural point of view, Re 2 O 7 can be divided into two fragments: a perrhenate anion (ReO 4 − ) and a perrhenyl cation (ReO 3 + ). Cleavage of Re 2 O 7 can be achieved in the presence of electrophiles or nucleophiles to give monomeric compounds of the general formula L−ReO 3 . 3 It was reported that Re 2 O 7 dissolves in polar solvents such as THF, CH 3 CN, and pyridine to form solvent adducts. 4 This unsymmetrical coordination enhances the reactivity of Re 2 O 7 toward alkyla...

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Metallorganische lewissäuren

Cited by 16 publications

References 11 publications

Surface Organometallic Chemistry: Easy Reductive Carbonylation of Silica-Supported [Re(CO)₃(OH)]₄to [Re₂(CO)₁₀] via Silica-Anchored [Re(CO)₅(OSi⋮)] and the Thermal Behavior of Silica-Supported [Re₂(CO)₁₀]

Surface Organometallic Chemistry: Easy Reductive Carbonylation of Silica-Supported [Re(CO)₃(OH)]₄to [Re₂(CO)₁₀] via Silica-Anchored [Re(CO)₅(OSi⋮)] and the Thermal Behavior of Silica-Supported [Re₂(CO)₁₀]

Rhenium(VII) Oxo and Imido Complexes: Synthesis, Structures, and Applications

Homogeneous Model Complexes for Supported Rhenia Metathesis Catalysts

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Metallorganische lewissäuren

Cited by 16 publications

References 11 publications

Surface Organometallic Chemistry: Easy Reductive Carbonylation of Silica-Supported [Re(CO)3(OH)]4to [Re2(CO)10] via Silica-Anchored [Re(CO)5(OSi⋮)] and the Thermal Behavior of Silica-Supported [Re2(CO)10]

Surface Organometallic Chemistry: Easy Reductive Carbonylation of Silica-Supported [Re(CO)3(OH)]4to [Re2(CO)10] via Silica-Anchored [Re(CO)5(OSi⋮)] and the Thermal Behavior of Silica-Supported [Re2(CO)10]

Rhenium(VII) Oxo and Imido Complexes: Synthesis, Structures, and Applications

Homogeneous Model Complexes for Supported Rhenia Metathesis Catalysts

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Product

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Surface Organometallic Chemistry: Easy Reductive Carbonylation of Silica-Supported [Re(CO)₃(OH)]₄to [Re₂(CO)₁₀] via Silica-Anchored [Re(CO)₅(OSi⋮)] and the Thermal Behavior of Silica-Supported [Re₂(CO)₁₀]

Surface Organometallic Chemistry: Easy Reductive Carbonylation of Silica-Supported [Re(CO)₃(OH)]₄to [Re₂(CO)₁₀] via Silica-Anchored [Re(CO)₅(OSi⋮)] and the Thermal Behavior of Silica-Supported [Re₂(CO)₁₀]