Untersuchungen über den Mechanismus der reduktiven Eliminierung des Biphenyl‐;Systems aus <i>cis</i>‐Diphenylbis‐(triphenylphosphan)platin(II)‐Verbindungen: Einfluß der Elektronendichten am Platin auf die Aktivierungsparameter

Brune, Hans Albert; Falck, Manfred; Hemmer, Reinhard; Alt, Helmut G.

doi:10.1002/cber.19841170903

Cited by 21 publications

(4 citation statements)

References 11 publications

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“…The first process has a much greater total activation energy than the second and is inconsistent with the absence of a free phosphine influence on the reductive elimination rates. The second process is also consistent with the majority of studies on related complexes. ,− Direct reductive elimination from the four-coordinate complexes is therefore considered to be operative (Scheme ).…”

Section: Resultssupporting

confidence: 76%

“…The second process is also consistent with the majority of studies on related complexes. 4, [26][27][28][29][30][31][32][33] Direct reductive elimination from the four-coordinate complexes is therefore considered to be operative (Scheme 1).…”

Section: Resultssupporting

confidence: 75%

“…Overall, these activation parameters are quite comparable to those for biaryl elimination from Pt((C 6 F 5 ) 2 PCH 2 CH 2 P-(C 6 F 5 ) 2 )(Ph) 2 in benzene (ΔH q = 27.6 ( 1 kcal/mol, ΔS q = -1.5 ( 1 cal/K 3 mol) 25 and fall into the range reported for elimination from a number of complexes of formula cis-Pt(P(C 6 H 4 X) 3 ) 2 (C 6 H 4 Y)(C 6 H 4 Z) (ΔH q = 23.4 ( 0.4 to 34 ( 2 kcal/mol, ΔS q = -5.9 ( 4.6 to 21 ( 7 cal/K 3 mol). 26 Computational Studies. The platinacycle reductive elimination process was evaluated computationally in the gas phase using DFT.…”

Section: Resultssupporting

confidence: 74%

“…The Δ S ⧧ values are small, as expected for a unimolecular reaction. Overall, these activation parameters are quite comparable to those for biaryl elimination from Pt((C 6 F 5 ) 2 PCH 2 CH 2 P(C 6 F 5 ) 2 )(Ph) 2 in benzene (Δ H ⧧ = 27.6 ± 1 kcal/mol, Δ S ⧧ = −1.5 ± 1 cal/K·mol) and fall into the range reported for elimination from a number of complexes of formula cis -Pt(P(C 6 H 4 X) 3 ) 2 (C 6 H 4 Y)(C 6 H 4 Z) (Δ H ⧧ = 23.4 ± 0.4 to 34 ± 2 kcal/mol, Δ S ⧧ = −5.9 ± 4.6 to 21 ± 7 cal/K·mol) …”

Section: Resultssupporting

confidence: 73%

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Syntheses, Structures, and Reductive Elimination Studies of Six-Membered Diaryl Platinacycle Complexes

Robinson

Sharp

2010

Organometallics

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The six-membered platinacycles PtL 2 (C 6 H 4 XC 6 H 4 ) (X = CH 2 , O, NMe; L = PEt 3 , L 2 = 1,3bis(diphenylphosphino)propane (dppp), 4,4 0 -bis-tert-butyl-2,2 0 -bipyridine ( t Bu 2 bpy)), have been prepared from cis-PtL 2 Cl 2 and the appropriate dilithio reagents. Reductive elimination studies on the platinacycles with L = PEt 3 show that the bridging group (X) dramatically influences the reductive elimination rate. Thermodynamic activation parameters were determined for the platinacycles and showed a ΔH q trend X = NMe , O < CH 2 with an essentially zero value for ΔS q . Rate constants at 95 °C show over a million-fold increase on going from X = CH 2 to X = NMe. DFT calculations support direct elimination without phosphine ligand loss and indicate a progressively earlier transition state in the series X = CH 2 , O, NMe. The earlier transition state and the accelerated rate are associated with the beginning of aromatization in the eliminating organic unit. Computed thermodynamic activation parameters are in good agreement with the experimental results.

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Section: Resultssupporting

confidence: 76%

Section: Resultssupporting

confidence: 75%

Section: Resultssupporting

confidence: 74%

Section: Resultssupporting

confidence: 73%

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Syntheses, Structures, and Reductive Elimination Studies of Six-Membered Diaryl Platinacycle Complexes

Robinson

Sharp

2010

Organometallics

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Synthesen und spektroskopische Untersuchungen substituierter cis‐ und trans‐Dichlorobis(triphenylphosphan)platin(II)‐Verbindungen

Brune¹,

Falck²,

Hemmer³

et al. 1984

Chem. Ber.

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Verbindungen des Typs cis-und trans-Dichlorobis(triphenylphosphan)platin(II) (3), deren an denPhosphor gebundene Phenyl-Ringe in yerschiedenen Positionen mit Substituenten unterschiedlichen elektronischen Charakters substituiert sind, werden dargestellt. Mit den Kopplungskonstanten 1J[1"Pt,31P] und den Platin-Chlor-Valenzschwingungsfrequenzen werden Kriterien fur die sichere Unterscheidung zwischen ckund truns-Konfiguration am Platin aufgezeigt; es besteht ein h e a r e r Zusammenhang zwischen der Summe der Substituenten-Konstanten der in das Triphenylphosphan eingefuhrten Substituenten und den Kopplungskonstanten 1J['gSPt,3'P]. Syntheses and Spectroscopic Investigations of Substituted cisand trans-Dichlorobis-(triphenylphosphane)platinum(II) CompoundsCompounds of the type cis-and truns-dichlorobis(triphenylphosphane)platinum(II) (3) with substituents of different electronic character in the phenyl rings bonded to phosphorus have been synthesized. The coupling constants 'J['9SPt,3'P] and the chloro-platinum valence vibrational frequencies are demonstrated to be criteria for unambiguous discrimination between cis-and trans-configurations at platinum; a linear correlation exists between the sum of the a-constants of the substituents at the triphenylphosphane and the coupling constants 'J['95Pt,31P].

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Synthesen von cis ‐ und trans ‐Bis(X‐phenyl)‐ bis(tributylphosphan)platin(II)‐Verbindungen mit Substituenten von π‐Akzeptor‐Charakter in den platingebundenen Phenyl‐Ringen

Müller

Brune

1985

Chem. Ber.

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In vorausgegangenen Arbeitenl -' ) untersuchten wir als Beispiel fur eine pericyclische Reaktion an einem ubergangsmetall kinetisch und mechanistisch die thermisch symmetrie-erlaubte regiospezifische Eliminierung des Biphenyl-Systems aus substituierten cis-Bjs(X-phenyl)bis(triphenylphosphan)platin(II)-Verbindungen. Zu diesem Zweck synthetisierten wir eine groSe Zahl von Verbindungen dieses Typs, die in den verschiedenen Positionen der unmittelbar an das Platin gebundenen Phenyl-Ringe Substituenten unterschiedlichen elektronischen Charakters trugen. Von besonderem Interesse waren fur diese Untersuchungen solche Verbindungen, deren einer Phenyl-Ring einen Substituenten mit Donator-Eigenschaften, der zweite dagegen einen mit Akzeptor-Charakter trug; denn kinetische Daten3,4) schienen anzudeuten, da13 die Eliminierung des Biphenyl-Systems durch eine Donator-Akzeptor-Wechselwirkung zwischen den beiden cis-stindigen PhenylRingen eingeleitet wird bzw. im ubergangszustand der Reaktion eine solche Wech-0 VCH Verlagsgesellschaft mbH, D

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Untersuchungen über den Mechanismus der reduktiven Eliminierung des Biphenyl‐;Systems aus cis‐Diphenylbis‐(triphenylphosphan)platin(II)‐Verbindungen: Einfluß der Elektronendichten am Platin auf die Aktivierungsparameter

Cited by 21 publications

References 11 publications

Syntheses, Structures, and Reductive Elimination Studies of Six-Membered Diaryl Platinacycle Complexes

Syntheses, Structures, and Reductive Elimination Studies of Six-Membered Diaryl Platinacycle Complexes

Synthesen und spektroskopische Untersuchungen substituierter cis‐ und trans‐Dichlorobis(triphenylphosphan)platin(II)‐Verbindungen

Synthesen von cis ‐ und trans ‐Bis(X‐phenyl)‐ bis(tributylphosphan)platin(II)‐Verbindungen mit Substituenten von π‐Akzeptor‐Charakter in den platingebundenen Phenyl‐Ringen

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