Metallinduzierte CC‐Einfachbindungsspaltung 5,5‐dialkylsubstituierter Cyclopentadiene durch Metallcarbonylkomplexe der 6. Nebengruppe

Eilbracht, Peter; Dahler, Peter; Mayser, Ulrich; Henkes, Erhard

doi:10.1002/cber.19801130322

Cited by 26 publications

(1 citation statement)

References 20 publications

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“…The reversibility of methyl transfer between the ruthenium center and the π-allyl ligand is similar in many regards to that seen by Green, Eilbracht, − Crabtree, , and most recently Wolczanski . In 1974, Benfield and Green reported the reversible transfer of an ethyl group between the Cp ligand and the metal in Cp 2 MoEtCl .…”

Section: Discussionsupporting

confidence: 70%

C−C and C−H Bond Activation at Ruthenium(II): The Stepwise Degradation of a Neopentyl Ligand to a Trimethylenemethane Ligand

1997

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Ruthenacyclobutane complexes (SiP3)(PMe3)Ru(CH2EMe2CH2) (SiP3 = MeSi(CH2PMe2)3; 1, E = C; 2, E = Si) were synthesized from (SiP3)(PMe3)RuCl2 (3) and 2 equiv of the Grignard reagents, Me3ECH2MgCl. Metallacycle 1 was found to reversibly interconvert with the allyl complex (SiP3)Ru(Me)(η3-CH2CMeCH2) (4) and PMe3 when heated above 75 °C. From the results of kinetic studies and thermolysis of labeled material, the interconversion is proposed to take place by reversible β-methyl elimination/insertion. Conversion of 1 to 4 is an endothermic process (ΔH° = 14.3 ± 1.1 kcal mol-1), but it is entropically favorable (ΔS° = 40.9 ± 2.8 cal K-1 mol-1) due to the loss of the PMe3 ligand. Activation parameters for the β-insertion were determined to be ΔH ⧧ = 26.0 ± 1.2 kcal mol-1 and ΔS ⧧ = −10.5 ± 0.9 cal K-1 mol-1. Allyl complex 4 has been isolated as a mixture of isomers (7:1 endo:exo). The mechanism of interconversion of 4 endo and 4 exo was determined by 1H{31P} NMR spectroscopy (EXSY) to be a process involving a stereochemically rigid, square-pyramidal η1-intermediate. Thermolysis of 4 leads to loss of CH4 and the production of the trimethylenemethane complex (SiP3)Ru(η4-C(CH2)3) (7). The solid state structures of 1 and 7 were determined by X-ray diffraction.

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Section: Discussionsupporting

confidence: 70%

C−C and C−H Bond Activation at Ruthenium(II): The Stepwise Degradation of a Neopentyl Ligand to a Trimethylenemethane Ligand

1997

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Stable and Catalytically Highly Active ansa Compounds with Cycloalkyl Moieties as Bridging Units

2009

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The complexes Mo{η5‐C5H4[CH(CH2)3]‐η1‐CH}(CO)3 (2a) and W{η5‐C5H4[CH(CH2)3]‐η1‐CH}CO)3 (2b) were synthesized by reacting spiro[4.2]bicyclo[4.1]deca‐6,8‐diene (1) with the tri(acetonitrile)tri(carbonyl)metal complexes M(CO)3(CH3CN)3 (M=Mo, W). Thermogravimetric (TGA) measurements confirm that the complexes are stable up to 140 °C in air in the solid state. The complexes 2a and 2b are very active catalysts at room temperature for the epoxidation of cyclooctene with tert‐butyl hydroperoxide (TBHP) as oxidant, reaching TOFs of up to 3650 h−1. Complex 2a achieves a quantitative product yield without formation of any by‐products within 1.5 h, outperforming previously published ansa compounds and performing on par with the cyclopentadienyltri(carbonyl)(halo)‐ or (alkyl)molybdenum compelxes CpMo(CO)3R (R=Hal, Me, Et).

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Synthesis and Catalytic Applications of ansa Compounds with Cycloalkyl Moieties as Bridging Units: A Comparative Study

et al. 2010

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Abstract:The molybdenum and tungsten compounds (MoA C H T U N G T R E N N U N G {h-CH}(CO) 3 ) (2a, 3a n = 3; 2b, 3b n = 4; 2c, 3c n = 5; 2d, 3d n = 6) were synthesized by reacting the spiro-bicyclic compounds 1a-d with theNMR spectroscopy, as well as X-ray diffraction studies, confirm the formation of an intramolecular ansa bridge. The complexes display a good stability in the solid state (stable up to 180 8C under air, as determined by thermogravimetric studies) and are highly active catalysts at room temperature (molybdenum compounds) or above (tungsten compounds) in olefin epoxidation. In the case of cyclooctene as substrate, TOFs up to ca. 11800 h À1 are obtained. Moreover, most of the catalysts described here display a high selectivity in the epoxidation of cis-and transstilbene. In addition, the novel complexes were compared with previously synthesized related compounds, at least matching their catalytic performances.

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Metallinduzierte CC‐Einfachbindungsspaltung 5,5‐dialkylsubstituierter Cyclopentadiene durch Metallcarbonylkomplexe der 6. Nebengruppe

Cited by 26 publications

References 20 publications

C−C and C−H Bond Activation at Ruthenium(II): The Stepwise Degradation of a Neopentyl Ligand to a Trimethylenemethane Ligand

C−C and C−H Bond Activation at Ruthenium(II): The Stepwise Degradation of a Neopentyl Ligand to a Trimethylenemethane Ligand

Stable and Catalytically Highly Active ansa Compounds with Cycloalkyl Moieties as Bridging Units

Synthesis and Catalytic Applications of ansa Compounds with Cycloalkyl Moieties as Bridging Units: A Comparative Study

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