Methyltrioxorhenium and Its Applications in Olefin Oxidation, Metathesis and Aldehyde Olefination

Kuehn, Fritz E.; Scherbaum, Andrea; Herrmann, Wolfgang A.

doi:10.1002/chin.200513282

Cited by 4 publications

(4 citation statements)

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“…The secondary building units (SBUs) are particularly relevant targets for functionalization because they can be thought of as nanoscale models of the metal oxides traditionally used as industrial catalyst supports. , Among supported OM catalysts, rhenium oxide-based systems stand out due to their activity at room temperature and their broad tolerance to a range of heterofunctionalized olefins when activated by main group alkyl species. ,, These characteristics contrast with molybdenum and tungsten systems, which are active only at significantly higher temperatures and are less tolerant of functionalized olefins. Important milestones in rhenium oxide chemistry were the discovery and efficient preparation , of methyltrioxorhenium (MTO), a molecule with diverse catalytic competency. − The most salient feature of this versatile model − for immobilized rhenium oxide species in the context of heterogeneous OM catalysis is its inability to catalyze this transformation until activated on an appropriate support. The surprisingly limited scope of supports capable of triggering OM activity from MTO include alumina, − silica–alumina, ,,− niobia, , and zeolite HY …”

Section: Introductionmentioning

confidence: 99%

Activation of Methyltrioxorhenium for Olefin Metathesis in a Zirconium-Based Metal–Organic Framework

et al. 2018

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The zirconium nodes of the metal-organic framework (MOF) known as NU-1000 serve as competent supports for the activation of methyltrioxorhenium (MTO) toward olefin metathesis. Itself inactive for olefin metathesis, MTO becomes an active catalyst only when immobilized on the strongly acidic Lewis acid sites of dehydrated NU-1000. Uptake of MTO at the dehydrated secondary building units (SBUs) occurs rapidly and quantitatively to produce a catalyst active in both gas- and liquid-phase processes. These results demonstrate for the first time the utility of MOF SBUs for olefin metathesis, an academically and industrially relevant transformation.

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Section: Introductionmentioning

confidence: 99%

Activation of Methyltrioxorhenium for Olefin Metathesis in a Zirconium-Based Metal–Organic Framework

et al. 2018

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“…Oxorhenium complexes have been developed for a broad range of catalytic applications in synthetic chemistry, − biomass conversion, − and environmental remediation. − Nonradioactive 185 Re/ 187 Re complexes have also been extensively studied as 186 Re, 188 Re, and 99m Tc surrogates for radiopharmaceutical development. − Since 1996, a number of Re V (O)(L N–O ) 2 X complexes (L N–O = monoanionic N–O chelates; X = Cl or Br prior to being replaced by solvents or alkoxides) have been synthesized . Specific L N–O ligands enable the Re center to exhibit novel catalytic activities, including hydrosilylation, , H 2 generation from silanes, C–H activation, aldol condensation, olefin epoxidation, and controlled supramolecular assembly .…”

Section: Introductionmentioning

confidence: 99%

Ligand Design for Isomer-Selective Oxorhenium(V) Complex Synthesis

Liu

Han³

et al. 2017

Inorg. Chem.

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Recently, N,N-trans Re(O)(L)X (L = monoanionic N-O chelates; X = Cl or Br prior to being replaced by solvents or alkoxides) complexes have been found to be superior to the corresponding N,N-cis isomers in the catalytic reduction of perchlorate via oxygen atom transfer. However, reported methods for Re(O)(L)X synthesis often yield only the N,N-cis complex or a mixture of trans and cis isomers. This study reports a geometry-inspired ligand design rationale that selectively yields N,N-trans Re(O)(L)Cl complexes. Analysis of the crystal structures revealed that the dihedral angles (DAs) between the two L ligands of N,N-cis Re(O)(L)Cl complexes are less than 90°, whereas the DAs in most N,N-trans complexes are greater than 90°. Variably sized alkyl groups (-Me, -CHPh, and -CHCy) were then introduced to the 2-(2'-hydroxyphenyl)-2-oxazoline (Hhoz) ligand to increase steric hindrance in the N,N-cis structure, and it was found that substituents as small as -Me completely eliminate the formation of N,N-cis isomers. The generality of the relationship between N,N-trans/cis isomerism and DAs is further established from a literature survey of 56 crystal structures of Re(O)(L)X, Re(O)(L)X, and Tc(O)(L)X congeners. Density functional theory calculations support the general strategy of introducing ligand steric hindrance to favor synthesis of N,N-trans Re(O)(L)X and Tc(O)(L)X complexes. This study demonstrates the promise of applying rational ligand design for isomeric control of metal complex structures, providing a path forward for innovations in a number of catalytic, environmental, and biomedical applications.

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“…135,136 MTO catalyzed deoxygenation reactions of biomass and biomasssurrogate molecules are extremely important, especially in the work of Toste, 137,138 Nicholas 139 and others and has been extensively reviewed elsewhere. [140][141][142][143][144][145] One specific instance where MDO's reactivity has been implicated is in the cleavage of lignin model compounds. MTO is converted to the active catalyst MDO in situ via hydrogen transfer and is active for the cleavage of the β-O-4 linkages in the lignin model compounds.…”

Section: Rheniummentioning

confidence: 99%