[2+2]-Cycloaddukte PH-funktioneller Phosphenium-Komplexe mit Alkylisothiocyanaten: Darstellung von C5R5(OC)2 (R=H, Me; M=Mo, W; R′=Me, Et, t-Bu) und Reaktion unter Beanspruchung der PH-Funktion

Malisch, Wolfgang; Grün, Klaus; Fey, Oliver; Baky, Christa Abd El

doi:10.1016/s0022-328x(98)00804-3

Cited by 16 publications

(3 citation statements)

References 30 publications

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“…Accordingly, the Ph 2 PH ligand in 5 is transformed into a phosphenium-type ligand in structures 6 and 7. [8] If intermediate 7 is short-lived and a 1,2-hydrogen shift from the cobalt to the phosphorus center (7!8) takes place, the lifetime of the cobalt-hydride intermediate 7 is reduced, which prohibits the formation of higher homologues through re-addition of the cobalt hydride to the 2-alkene and so on. The steric bulk of the dppp ligand must be responsible for the kinetically controlled formation of the Z isomer.…”

Section: Methodsmentioning

confidence: 99%

An Alternative Mechanism for the Cobalt‐Catalyzed Isomerization of Terminal Alkenes to (Z)‐2‐Alkenes

2014

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Section: Methodsmentioning

confidence: 99%

An Alternative Mechanism for the Cobalt‐Catalyzed Isomerization of Terminal Alkenes to (Z)‐2‐Alkenes

2014

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“…Dabei geht der Ph 2 PH-Ligand in 5 in einen Phospheniumartigen Liganden in den Strukturen 6 und 7 über. [8] Wenn das Intermediat 7 kurzlebig ist und eine 1,2-H-Wanderung von Cobalt zu Phosphor (7!8) stattfindet, hat das CobalthydridIntermediat 7 nur eine kurze Lebensdauer, wodurch die Bildung von hçheren Homologen durch wiederholte Addition des Cobalthydrids an das 2-Alken und hçhere Isomere unterbunden wird. Die kinetisch kontrollierte Bildung des ZIsomers ist auf den sterischen Anspruch des dppp-Liganden zurückzuführen.…”

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Ein alternativer Mechanismus für die Cobalt‐katalysierte Isomerisierung von terminalen Alkenen zu (Z)‐2‐Alkenen

2014

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Die Cobalt-katalysierte selektive Isomerisierung von terminalen Alkenen hin zum thermodynamisch weniger stabilen (Z)-2-Alken bei Raumtemperatur läuft über einen neuartigen Mechanismus ab, der die Übertragung eines Wasserstoffs von einem Ph 2 PH-Liganden zur Ausgangsverbindung und die Bildung eines Phospheniumkomplexes, aus dem durch eine 1,2-H-Wanderung der Ph 2 PH-Komplex regeneriert wird, einschließt.

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“…This process rarely occurs in an intermolecular manner, [51] but is entropically favored intramolecularly. [52] In the case of the N-protonated P-oxide 6·H…”

mentioning

confidence: 99%

Computational Studies on Azaphosphiridines, or How to Effect Ring‐Opening Processes through Selective Bond Activation

Espinosa

Streubel

2011

Chemistry A European J

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The relative energies of azaphosphiridine and its isomers, the ring stability towards valence isomerization, and the ring strain, as well as the kinetics and thermodynamics of possible ring-opening reactions of P(III) derivatives (1-5) and P(V) chalcogenides (6-9; O to Te), were studied at high levels of theory (up to CCSD(T)). The barrier to inversion at the nitrogen atom in the trimethyl-substituted P(III) derivative 5 increases from 12.11 to 15.25 kcal mol(-1) in the P-oxide derivative 6 (P(V)); the relatively high barrier to inversion at the phosphorus in 5 (75.38 kcal mol(-1)) points to a configurationally stable center (MP2/def2-TZVPP//BP86/def2-TZVP). The ring strain for azaphosphiridine 5 (av. 22.6 kcal mol(-1)) was found to increase upon P-oxidation (6) (30.8 kcal mol(-1); same level of theory). Various ring-bond-activation processes were studied: N-protonation of P(III) (5) and P(V) (6, 7) derivatives leads to highly activated species that readily undergo P-N bond cleavage. In contrast, metal chlorides such as LiCl, CuCl, CuCl(2), BeCl(2), BCl(3), AlCl(3), TiCl(3), and TiCl(4) show little P-N bond activation in 5 and 7. Remarkably, TiCl(3) selectively activates the C-N bond, and induces stronger bond activation for P(V) (6, 7) than for P(III) azaphosphiridines (5). The ring-expanding rearrangement of P(V) azaphosphiridines 6-9 to yield P(III) 1,3,2-chalcogena-azaphosphetidines 32 a-d is predicted to be preferred for the heavier chalcogenides 7-9, but not for the P-oxide 6. The first comparative analysis of three bond strength parameters is presented: 1) the electron density at bond critical points, 2) Wiberg's bond index, and 3) the relaxed force constant. This reveals the usefulness of these parameters in assessing the degree of ring bond activation.

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[2+2]-Cycloaddukte PH-funktioneller Phosphenium-Komplexe mit Alkylisothiocyanaten: Darstellung von C5R5(OC)2 (R=H, Me; M=Mo, W; R′=Me, Et, t-Bu) und Reaktion unter Beanspruchung der PH-Funktion

Cited by 16 publications

References 30 publications

An Alternative Mechanism for the Cobalt‐Catalyzed Isomerization of Terminal Alkenes to (Z)‐2‐Alkenes

An Alternative Mechanism for the Cobalt‐Catalyzed Isomerization of Terminal Alkenes to (Z)‐2‐Alkenes

Ein alternativer Mechanismus für die Cobalt‐katalysierte Isomerisierung von terminalen Alkenen zu (Z)‐2‐Alkenen

Computational Studies on Azaphosphiridines, or How to Effect Ring‐Opening Processes through Selective Bond Activation

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