Formation and reactivity of palladium hydride complexes, [(PPh3)3PdH]+ and [(PPh3)2Pd(μ-H)(μ-CO)Pd(PPh3)2]+, in aqueous trifluoroacetic acid solutions

Зудин, В. Н.; Chinakov, V. D.; Nekipelov, V. M.; Likholobov, V. A.; Yermakov, Yu. I.

doi:10.1016/0022-328x(85)87419-2

Cited by 57 publications

(51 citation statements)

References 11 publications

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“…In the present work the precursor is [PdCl 2 (dppf)], but since it is well known that water is capable of coordinating Pd(II) with the formation of aqua-complexes and also that the monomers are capable to coordinate Pd(II) [41,42], it is plausible to suppose that [PdCl 2 (dppf)] undergoes equilibrium 1 (Scheme 1) [28,43]. Upon increasing the concentration of H 2 O, the formation of a cationic aqua-complex is favored also by the increasing of the dielectric constant of the reaction medium, which favors the separation of the charges.…”

Section: Proposed Catalytic Cyclementioning

confidence: 99%

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Terpolymerization of propene and ethene with carbon monoxide catalyzed by [PdCl2(dppf)] in HCOOH–H2O as a solvent [dppf=1,1′-bis(diphenylphosphino)ferrocene]

Vavasori¹,

Ronchin²,

Toniolo³

2010

Applied Catalysis A: General

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a b s t r a c tThe [PdCl 2 (dppf)] complex efficiently catalyzes the terpolymerization of propene and ethene with carbon monoxide in HCOOH-H 2 O as a solvent, when H 2 O concentration ranges between 50 and 65 molar %. The productivity, the melting temperature and the viscosity average molecular weight of the terpolymer depend on the propene concentration and on the reaction time.The NMR analysis of the polymer composition indicates the presence along the chain mainly of ethene-CO units together with a low percent of propene-CO units.A reaction mechanism is proposed and discussed.

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Section: Proposed Catalytic Cyclementioning

confidence: 99%

“…Moreover, the acid might destabilize the ␤-or ␥-chelates which are formed during the chain growing process through protonation of the oxygen atom of the coordinating keto group, thus favoring the insertions of the monomers [43].…”

Section: Proposed Catalytic Cyclementioning

confidence: 99%

Terpolymerization of propene and ethene with carbon monoxide catalyzed by [PdCl2(dppf)] in HCOOH–H2O as a solvent [dppf=1,1′-bis(diphenylphosphino)ferrocene]

Vavasori¹,

Ronchin²,

Toniolo³

2010

Applied Catalysis A: General

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“…Formation of the cationic hydride (PdL 3 H) + (TFA) − was observed by NMR when Pd(PPh 3 ) 4 was allowed to react with a 70% aqueous solution of HTFA at −25 • C [23,24] or when a solution of Pd(OAc) 2 and tppts (tppts = P(C 6 H 4 -m-SO 3 Na) 3 ) in a 60% (v/v) aqueous trifluoroacetic acid (HTFA). The formation of the hydride occurs via reduction of Pd(II) to Pd(0) by H 2 O-CO followed by oxidation of Pd(0) with a proton [25].…”

Section: Effect Of the Reaction Conditions On The Catalyst Activitymentioning

confidence: 99%

Highly active [Pd(AcO)2(dppp)] catalyst for the CO-C2H4 copolymerization in H2O-CH3COOH solvent [dppp = 1,3-bis(diphenylphosphino)propane]

Vavasori¹,

Toniolo²,

Cavinato

et al. 2003

Journal of Molecular Catalysis A: Chemical

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In MeOH, [Pd(AcO) 2 (dppp)] becomes an efficient catalyst for the perfectly alternated CO-C 2 H 4 copolymerization when used in combination of a relatively large amount of CH 3 COOH (CH 3 COOH/Pd, ca. 2.0 × 10 4 ). Under 4.56 MPa (CO/C 2 H 4 = 1/1), at 90 • C, 7.5 kg polyketone/g Pd * h are obtained. A significantly higher productivity is obtained in H 2 O-CH 3 COOH, in place of MeOH (27.5 kg polymer/g Pd * h under 4.56 MPa (CO/C 2 H 4 = 1/1), 90 • C, H 2 O = 37% (mol/mol)). Under these conditions the catalyst undergoes only a minor deactivation with time as after 3 h the productivity decreases only by ca. 10%.The 13 C NMR analysis shows that [Pd(AcO) 2 (dppp)] in CH 3 COOH-H 2 O yields a perfectly alternated polyketone of ca. 8000 g/mol bearing only ketonic end groups. During the course of the copolymerization reaction CO 2 forms in significant amount. These findings suggest that the insertion of C 2 H 4 into Pd-H bond starts the catalytic cycle, and that alternating insertions of the monomers followed by protonolysis of a Pd-C bond of a Pd-CH 2 -CH 2 -(CO-C 2 H 4 ) n -H growing chain yields the polymer with only keto ending groups and a Pd-OH species; a reaction closely related to the WGS reproduces the starting Pd-hydride; deprotonation of this species to inactive Pd(0) is prevented by the acid.

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“…of PPh 3 . The reduction occurs with concomitant formation of CO 2 , probably via a reaction closely related to the water gas shift reaction through the intermediacy of a Pd(II)-(COOH) species [64][65][66]:…”

Section: Reactivity With Water and With Water/tsohmentioning

confidence: 99%

New carboalkoxybis(triphenylphosphine)palladium(II) cationic complexes: Synthesis, characterization, reactivity and role in the catalytic hydrocarboalkoxylation of ethene. X-ray structure of trans-[Pd(COOMe)(TsO)(PPh3)2]·2CHCl3

Amadio¹,

Cavinato²,

Dolmella³

et al. 2009

Journal of Molecular Catalysis A: Chemical

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a b s t r a c tThe cationic complexes trans- [Pd(COOR) (R = n-Pr, iso-Pr, n-Bu, iso-Bu, sec-Bu). They have been characterised by IR, 1 H NMR and 31 P NMR spectroscopies. The X-ray investigation of trans-[Pd(COOMe)(TsO)(PPh 3 ) 2 ] reveals that the palladium center is surrounded in a virtually square planar environment realized by two PPh 3 trans to each other, the carbon atom of the carbomethoxy ligand and an oxygen atom of the p-toluensulfonate anion, with two crystallization molecules of CHCl 3 . The Pd-O-S angle, 151.9 (3)• , is very wide, probably due to the interaction of one CHCl 3 molecule with the complex inner core. The carbomethoxy derivatives react with R OH yielding the corresponding R carboalkoxy derivative (R = Et, n-Pr and iso-Pr); ethene does not insert into the Pd-COOMe bond; decarbomethoxylation occurs when treated with TsOH/H 2 O in MeOH at 50• C. All the carboalkoxy are precursors for the catalytic carboalkoxylation of ethene if used in combination of PPh 3 and TsOH, better in the presence of some water. Experimental evidences are more in favor of the so-called "hydride" mechanism rather than the "carbomethoxy" mechanism.

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Formation and reactivity of palladium hydride complexes, [(PPh3)3PdH]+ and [(PPh3)2Pd(μ-H)(μ-CO)Pd(PPh3)2]+, in aqueous trifluoroacetic acid solutions

Cited by 57 publications

References 11 publications

Terpolymerization of propene and ethene with carbon monoxide catalyzed by [PdCl2(dppf)] in HCOOH–H2O as a solvent [dppf=1,1′-bis(diphenylphosphino)ferrocene]

Terpolymerization of propene and ethene with carbon monoxide catalyzed by [PdCl2(dppf)] in HCOOH–H2O as a solvent [dppf=1,1′-bis(diphenylphosphino)ferrocene]

Highly active [Pd(AcO)2(dppp)] catalyst for the CO-C2H4 copolymerization in H2O-CH3COOH solvent [dppp = 1,3-bis(diphenylphosphino)propane]

New carboalkoxybis(triphenylphosphine)palladium(II) cationic complexes: Synthesis, characterization, reactivity and role in the catalytic hydrocarboalkoxylation of ethene. X-ray structure of trans-[Pd(COOMe)(TsO)(PPh3)2]·2CHCl3

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