The mechanisms of thermal decomposition of dialkylbis(triethylphosphine)-platinum (II) complexes

Whitesides, G. M.

doi:10.1351/pac198153010287

Cited by 37 publications

(11 citation statements)

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“…We have provided evidence that the rate-determining step of the reaction of platinum enolates to form alkane and free enone is β-hydrogen elimination. However, kinetic data reported previously on the reactions of dialkylplatinum complexes in the presence of added phosphine have indicated that β-hydrogen elimination is reversible and subsequent reductive elimination or dissociation of alkene is rate limiting 15,16. We observed a primary kinetic isotope effect in our studies of the reaction of dialkylplatinum complex 10 in the presence of PPh 3 ( k H / k D = 2.5 ± 0.1).…”

Section: Discussionsupporting

confidence: 50%

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Mechanistic Study of β-Hydrogen Elimination from Organoplatinum(II) Enolate Complexes

Alexanian

Hartwig

2008

J. Am. Chem. Soc.

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A detailed mechanistic investigation of the thermal reactions of a series of bisphosphine alkylplatinum(II) enolate complexes is reported. The reactions of methylplatinum enolate complexes in the presence of added phosphine form methane and either free or coordinated enone, depending on the steric properties of the enone. Kinetic studies were conducted to determine the relationship between the rates and mechanism of β-hydrogen elimination from enolate complexes and the rates and mechanism of β-hydrogen elimination from alkyl complexes. The rates of reactions of the enolates were inversely dependent on the concentration of added phosphine, indicating that β-hydrogen elimination from the enolate complexes occurs after reversible dissociation of a phosphine. A normal, primary kinetic isotope effect was measured, and this effect was consistent with ratelimiting β-hydrogen elimination or C-H bond-forming reductive elimination to form methane. Reactions of substituted enolate complexes were also studied to determine the effect of the steric and electronic properties of the enolate complexes on the rates of β-hydrogen elimination. These studies showed that reactions of the alkylplatinum enolate complexes were retarded by electron-withdrawing substituents on the enolate and that reactions of enolate complexes possessing alkyl substituents at the β-position occurred at rates that were similar to those of complexes lacking alkyl substituents at this position. Despite the trend in electronic effects on the rates of reactions of enolate complexes and the substantial electronic differences between an enolate and an alkyl ligand, the rates of decomposition of the enolate complexes were similar to those of the analogous alkyl complexes. To the extent that the rates of reaction of the two types of complex are different, those involving β-hydrogen elimination from the enolate ligand were faster. A difference between the identity of the rate-determining step for decomposition of the two classes of complexes and an effect of stereochemistry on the selectivity for β-hydrogen elimination are possible origins of the observed phenomena.

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Section: Discussionsupporting

confidence: 50%

“…Some of the first detailed mechanistic studies in this area involved the thermolysis of bisphosphine platinum(II) dialkyl complexes 15,16. These systems yielded alkenes, alkanes, and platinum(0) complexes.…”

Section: Introductionmentioning

confidence: 99%

Mechanistic Study of β-Hydrogen Elimination from Organoplatinum(II) Enolate Complexes

Alexanian

Hartwig

2008

J. Am. Chem. Soc.

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“…While similar phosphine abstraction was observed by using other silver salts such as AgPF 6 and AgOTf and with other monodentate phosphine ligands, no removal of the chelating tertiary phosphines by silver salts was found.…”

Section: Generation Of Cationic Monoorganopalladium Complexes Having supporting

confidence: 63%

“…Complexes having PF 6 − as counter anion showed the reactivity toward CO insertion similar to the complexes having the weakly coordinating anion BF 4 − . Complexes having PF 6 − as counter anion showed the reactivity toward CO insertion similar to the complexes having the weakly coordinating anion BF 4 − .…”

Section: Equationmentioning

confidence: 80%

Chemistry of Monoorganopalladium Complexes Relevant to Catalysis

Yamamoto

Kayaki

Nagayama

et al. 2000

Synlett

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Neutral and cationic organopalladium complexes have been prepared as models for active intermediates involved in palladium-catalyzed reactions. Comparison of the reactivities of the neutral and cationic complexes revealed the much higher reactivities of the latter toward b-elimination and olefin or CO insertion. Generation of the solvent-coordinated hemilabile site on the cationic organopalladium complexes was indicated as a dominant factor in enhancing the reactivities. Utilizing the reactivity of an acylpalladium complex toward hydrogen, a novel, selective, and environmentally benign hydrogenation process catalyzed by palladium complexes to give various aldehydes has been developed.

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“…3,4 In parallel, numerous mechanistic studies have been performed on these oxidized systems to probe the different elementary steps of the mechanisms of C-H bond activation and functionalization. [5][6][7][8][9][10][11][12] On the other hand, Pt(0) fragments have been studied by very few groups, despite significant early findings. In particular, Halpern et al described in 1978 the ability of the complex [(PPh 3 ) 2 Pt(H)(CH 3 )] to readily eliminate methane at low temperature (À25 1C), generating the transient 14 electron complex that could be trapped with triphenylphosphine to form the stable 16 electron Pt(0) complex.…”

mentioning

confidence: 99%

Room temperature reversible C–H activation mediated by a Pt(0) center, and stoichiometric biphenyl formation via solvent activation

et al. 2012

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The mechanisms of thermal decomposition of dialkylbis(triethylphosphine)-platinum (II) complexes

Cited by 37 publications

References 0 publications

Mechanistic Study of β-Hydrogen Elimination from Organoplatinum(II) Enolate Complexes

Mechanistic Study of β-Hydrogen Elimination from Organoplatinum(II) Enolate Complexes

Chemistry of Monoorganopalladium Complexes Relevant to Catalysis

Room temperature reversible C–H activation mediated by a Pt(0) center, and stoichiometric biphenyl formation via solvent activation

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