Formation, structure, and reactivity of palladium superoxo complexes

Talsi, E. P.; Babenko, V. P.; Shubin, A. A.; Chinakov, V. D.; Nekipelov, V. M.; Zamaraev, K. I.

doi:10.1021/ic00270a012

Cited by 13 publications

(6 citation statements)

References 1 publication

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“…complexes of Pd) in this process or in the formation of 2 . This is especially true given the known formation of paramagnetic Pd superoxo complexes in mixtures of Pd 3 (OAc) 6 with H 2 O 2 . − In the mechanism proposed in Scheme , acetic acid and other protic sources play a key role in converting 2 into the active catalyst 1 or 6 , as determined from the kinetic studies on isolated 2 , and the catalysis and isotope exchange studies utilizing 2 as a precatalyst.…”

Section: Resultsmentioning

confidence: 99%

Catalytic Role of Multinuclear Palladium–Oxygen Intermediates in Aerobic Oxidation Followed by Hydrogen Peroxide Disproportionation

et al. 2015

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Aerobic oxidation of alcohols are catalyzed by the Pd-acetate compound [LPd(OAc)]2(OTf)2 (L = neocuproine = 2,9-dimethyl-1,10-phenanthroline) to form ketones and the release of hydrogen peroxide, but the latter rapidly undergoes disproportionation. We employ a series of kinetic and isotope labeling studies made largely possible by electrospray ionization mass spectrometry to determine the role of intermediates in causing this complex chemical transformation. The data suggested that multiple catalytic paths for H2O2 disproportionation occur, which involve formation and consumption of multinuclear Pd species. We find that the trinuclear compound [(LPd)3(μ(3)-O)2](2+), which we have identified in a previous study, is a product of dioxygen activation that is formed during aerobic oxidations of alcohols catalyzed by [LPd(OAc)]2(OTf)2. It is also a product of hydrogen peroxide activation during disproportionation reactions catalyzed by [LPd(OAc)]2(OTf)2. The results suggest that this trinuclear Pd compound is involved in one of the simultaneous mechanisms for the reduction of oxygen and/or the disproportionation of hydrogen peroxide during oxidation catalysis. Electrospray ionization mass spectrometry of hydrogen peroxide disproportionation reactions suggested the presence of other multinuclear Pd-O2 species in solution. Theoretical calculations of these compounds yield some insight into their structure and potential chemistry.

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Section: Resultsmentioning

confidence: 99%

Catalytic Role of Multinuclear Palladium–Oxygen Intermediates in Aerobic Oxidation Followed by Hydrogen Peroxide Disproportionation

et al. 2015

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“…(14) Reaction (14) is, most likely, the rate determining step of hydrogen peroxide decomposition in the presence of the tetraaquapalladium(II) complex w = k 14 …”

Section: Resultsmentioning

confidence: 99%

“…Second, being a strong electron acceptor, a C(NO 2 ) 4 molecule reacts efficiently with the low valence metal species (in this case, Pd I ). However, the influence of tetranitromethane on the kinetics of re action (1) can be considered as a fact confirming that reaction (14) is a rate determining step, because the oxi dation of any above mentioned species with tetranitro methane prevents reactions (16)- (19) or (21), (22), due to which the consumption rate of hydrogen peroxide de creases twofold.…”

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confidence: 94%

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Kinetics and mechanism of hydrogen peroxide decomposition in the presence of the tetraaquapalladium(II) complex

2005

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Kinetics of hydrogen peroxide decomposition in the presence of the tetraaquapalladium(II) complex in an aqueous solution at 40-70 °C was studied. The reaction rate is the first order with respect to the concentration of both Pd II and H 2 O 2 and the negative first order with respect to perchloric acid. Using free radicals traps, the reaction mechanism was found to differ from the traditional free radical mechanism known for d metal aqua ions and proceeds with out generation of hydroxyl radicals. The kinetic data obtained suggest a mechanism involving the formation of an intermediate palladium complex with oxygen.

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“…Subsequently, palladium superoxo complexes possessing similar oxidation properties have been prepared using KO 2 instead of H 2 O 2 , and also from Pd(OPr) 2 [24]. Scheme 2.…”

Section: Stoichiometric Reactionsmentioning

confidence: 99%

Pd-mediated epoxidation of olefins

Мuzart

2007

Journal of Molecular Catalysis A: Chemical

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Formation, structure, and reactivity of palladium superoxo complexes

Cited by 13 publications

References 1 publication

Catalytic Role of Multinuclear Palladium–Oxygen Intermediates in Aerobic Oxidation Followed by Hydrogen Peroxide Disproportionation

Catalytic Role of Multinuclear Palladium–Oxygen Intermediates in Aerobic Oxidation Followed by Hydrogen Peroxide Disproportionation

Kinetics and mechanism of hydrogen peroxide decomposition in the presence of the tetraaquapalladium(II) complex

Pd-mediated epoxidation of olefins

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