C–C coupling reaction of pyridine derivatives at the dimethyl rare-earth metal cation [YMe2(THF)5]+: A DFT investigation

Yahia, Ahmed; Kramer, Mathias U.; Okuda, Jun; Maron, Laurent

doi:10.1016/j.jorganchem.2010.09.003

Cited by 14 publications

(9 citation statements)

References 34 publications

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“…All the above theoretical observations account for the low barrier for this process compared to that reported in the literature. 37 Finally, C-C coupling is exothermic by 24.5 kcal mol −1 and the overall exothermicity is 51.1 kcal mol −1 with respect to starting materials.…”

Section: Papermentioning

confidence: 98%

Computational insights into carbon–carbon homocoupling reactions mediated by organolanthanide(iii) complexes

2014

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Homocoupling of terminal alkynes into trienediyl complexes by alkyl samarocenes is known experimentally. By means of computational techniques, we investigated the mechanism of this reaction in detail. The overall reaction sequence is: σ-bond metathesis, dimerisation of metallocenes, and homocoupling of two acetylides into trienediyl. We show that the rate-determining step corresponds to the homocoupling of two anionic acetylides. This coupling takes place at a bis-samarocene dimer complex in which the bridging mode of the two acetylide moieties is critical for the reaction to proceed. The limited energy barrier for the homocoupling of the carbanions originates from a synergistic effect of the two samarium centres within the dimer. Variation of the steric demand of both substrates and lanthanocenes allowed rationalising all the experimental data available for these systems.

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Section: Papermentioning

confidence: 98%

Computational insights into carbon–carbon homocoupling reactions mediated by organolanthanide(iii) complexes

2014

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“…[56] Calculations on the monocation [Y(h 2 -C,N-C 5 H 4 N) 2 (NC 5 H 5 ) 5 ][BPh 4 ] suggest that a C À C bond-formation step that would convert the coordinated pyridyl ligands into neutral bipyridine could occur through a single-electron reductive CÀC coupling; forming a bound bipyridyl radical anion. [57] Shen and co-workers reported the activation of the quinoline ligand at the 2 position in yttrium and ytterbium bis(3,5-di-tert-butylsalicylidene)-8-aminoquinoline (L quin ) complexes. (L quin )Ln(N(SiMe 3 ) 2 ) (52-Ln: Ln = Y, Yb) was accessible at low temperatures, while higher temperatures afforded 51-Ln and 53-Ln, with 53-Ln as the proposed intermediate.…”

Section: Chelation-assisted or Directed Càh Activationmentioning

confidence: 99%

“…The complexes all metalate pyridine, the reaction proceeding after the initial coordination of the pyridine molecule, forming for example [Y(η 2 ‐ C , N ‐C 5 H 4 N)(NC 5 H 5 ) 6 ] 2+ [BPh 4 ] 2 − ( 50 ), which retains the cationic charge (Scheme ) 56. Calculations on the monocation [Y(η 2 ‐ C , N ‐C 5 H 4 N) 2 (NC 5 H 5 ) 5 ][BPh 4 ] suggest that a CC bond‐formation step that would convert the coordinated pyridyl ligands into neutral bipyridine could occur through a single‐electron reductive CC coupling; forming a bound bipyridyl radical anion 57…”

Section: σ‐Bond Metathesismentioning

confidence: 99%

CH Bond Activation by f‐Block Complexes

et al. 2014

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Most homogeneous catalysis relies on the design of metal complexes to trap and convert substrates or small molecules to value-added products. Organometallic lanthanide compounds first gave a tantalizing glimpse of their potential for catalytic C-H bond transformations with the selective cleavage of one C-H bond in methane by bis(permethylcyclopentadienyl)lanthanide methyl [(η(5) -C5 Me5 )2 Ln(CH3 )] complexes some 25 years ago. Since then, numerous metal complexes from across the periodic table have been shown to selectively activate hydrocarbon C-H bonds, but the challenges of closing catalytic cycles still remain; many f-block complexes show great potential in this important area of chemistry.

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Section: Chelatunterstützte Oder Direkte C-h-aktivierungunclassified

“…Dabei wird ein gebundenes Bipyridylradikalanion gebildet. [55] Shens Gruppe berichtete über die Aktivierung des Chinolinliganden in 2-Position in Yttrium-und Ytterbiumkomplexen von Bis(3,5-di-tert-butylsalicyliden)-8-aminochinolin (L quin ). [(L quin )Ln{N(SiMe 3 ) 2 }] (52-Ln: Ln = Y, Yb) ist bei tiefen Temperaturen zugänglich, während hçhere Temperaturen zur Bildung von 51-Ln und 53-Ln führen.…”

Section: Chelatunterstützte Oder Direkte C-h-aktivierungunclassified

C‐H‐Aktivierung mit Komplexen der f‐Block‐Elemente

et al. 2014

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Homogene Katalyse hängt zu erheblichen Teilen von der Synthese von Metallkomplexen ab, die in der Lage sind, (niedermolekulare) Substrate zu binden und zu wertvolleren Produkten umzusetzen. Einen ersten Vorgeschmack der katalytischen C‐H‐Aktivierung mit metallorganischen Lanthanoidkomplexen gab es vor etwa 25 Jahren, als es gelang, mit Bis(pentamethylcyclopentadenyl)lanthanoid‐Methylkomplexen [(η5‐(C5Me5)2Ln(CH3)] eine C‐H‐Bindung von Methan zu spalten. In der Zwischenzeit wurden zahlreiche Metallkomplexe aus dem ganzen Periodensystem gefunden, die selektiv C‐H‐Bindungen aktivieren können, aber die Herausforderung, einen geschlossenen Katalysezyklus zu etablieren, bleibt bestehen. Viele f‐Block‐Komplexe scheinen aber über großes Potenzial auf diesem wichtigen Gebiet zu verfügen.

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C–C coupling reaction of pyridine derivatives at the dimethyl rare-earth metal cation [YMe2(THF)5]+: A DFT investigation

Cited by 14 publications

References 34 publications

Computational insights into carbon–carbon homocoupling reactions mediated by organolanthanide(iii) complexes

Computational insights into carbon–carbon homocoupling reactions mediated by organolanthanide(iii) complexes

CH Bond Activation by f‐Block Complexes

C‐H‐Aktivierung mit Komplexen der f‐Block‐Elemente

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