Chemistry of diamino-ligated methylpalladium(II) alkoxides and aryloxides (Part II): methoxide formation and carbonylation reactions

Kapteijn, Gerardus M.; Dervisi, Athanasia; Verhoef, Michel J.; Frederik, M.A.; Broek, Hans van den; Grove, David M.; Koten, Gerard van

doi:10.1016/0022-328x(96)06171-2

Cited by 28 publications

(24 citation statements)

References 63 publications

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“…1 The isoelectronic relationship between alkoxide and alkyl ligands suggests that they may display similar chemistry. Indeed, low-valent group 10 metal-oxygen bonds have been shown to participate in a number of typical organometallic reactions, including C-O bond forming reductive elimination, 2 β-H elimination, 3 and insertion reactions with unsaturated molecules such as CO [4][5][6][7][8][9][10][11][12][13] and alkenes. 14 However, the presence of lone pairs on the oxygen atom and the "hard" character of O-based ligands point to differences in stability and reactivity that may occur for these species relative to carbon-based analogues.…”

Section: Introductionmentioning

confidence: 99%

“…The best characterized CO migratory reactions with Ni−O bonds involve complexes featuring aryloxide ligands such as Ni(Me)(O- p -C 6 H 4 CN)L 2 (L = PEt 3 ; L 2 = 2,2‘-bipyridyl), for which spectroscopic evidence for the formation of an acyl intermediate was found, indicating a greater reactivity of the Ni−Me bond in this case 5c 5a, although the reasons for this remain unclear. A key role for the O-based lone pairs in facilitating the migratory insertion process has been identified, although the relative strengths of the M−O and M−C bonds may also be important …”

Section: Introductionmentioning

confidence: 99%

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Theoretical Study of CO Migratory Insertion Reactions with Group 10 Metal−Alkyl and −Alkoxide Bonds

Macgregor

Neave

2003

Organometallics

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The results of density functional calculations on the alternative migratory insertion reactions of CO with the M−OMe and M−Me bonds of group 10 M(Me)(OMe)(PH3)2 model systems are reported. For all three metals insertion into the M−OMe bond to form methoxycarbonyl products is thermodynamically favored over insertion into the M−Me bond to give acyls. This preference is small when M = Ni (ΔΔE R = 3 kcal/mol) but increases down the triad and becomes significant for M = Pt (ΔΔE R = 12 kcal/mol). Both associative five-coordinate and phosphine displacement four-coordinate mechanisms for migratory insertion were considered. For Ni associative mechanisms are more accessible and the lowest energy pathway is for reaction with the Ni−Me bond. With Pd and Pt the five- and four-coordinate pathways are close in energy, and for Pd there is a small kinetic preference for insertion into the Pd−OMe bond. For Pt however there is a clear kinetic preference for reaction with the Pt−OMe bond. During migratory insertion into M−OMe bonds the methoxide ligand rotates in the transition state to allow the participation of an oxygen lone pair in C−O bond formation while maintaining some residual M···OMe interaction. This M···OMe interaction is retained to some extent in the three-coordinate methoxycarbonyl species formed along the four-coordinate pathways. For an isostructural series of reactive species the trend in activation energy is always Ni < Pd ≪ Pt for reaction with the M−Me bond and Ni > Pd < Pt (with Pt > Ni) for reaction with the M−OMe bond. Trends in the computed thermodynamic and kinetic data of the alternative migratory insertions can be understood in terms of metal−ligand homolytic bond strengths. All M−C bonds studied show a marked increase down the group 10 triad, whereas much less variation is seen in the M−OMe bonds, which results in reaction with the M−OMe bonds being generally favored. A key additional driving force, however, is the stronger C−O bond formed in the methoxycarbonyl product compared to the C−C bond of the alternative acyl species.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Theoretical Study of CO Migratory Insertion Reactions with Group 10 Metal−Alkyl and −Alkoxide Bonds

Macgregor

Neave

2003

Organometallics

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“…Complex Am may evolve through the stepwise substitution of its TFA – ligands with other donors in solution, such as carbon monoxide, alkene (in the dihapto bonding mode), or a methanol solvent molecule. As suggested in the literature, − methanol likely precedes the CO coordination to give the adduct [(N-N)Pd(TFA)(CH 3 OH)] + ·[TFA] − , 2m a , in Figure , where the two counterions are held together by a H-bonding interaction with O 3 –H and H···O 1 distances of 1.04 and 1.48 Å, respectively.…”

Section: Resultsmentioning

confidence: 71%

“…The Pd complex reacts with the alcohol, allowing the formation of the active species B . The successive insertion of CO leads to the alkoxycarbonyl–palladium complex C , where the subsequent alkene’s coordination and insertion afford the five-membered palladacycle D . , From the latter, the complex E is obtained via another CO insertion passing through a six-membered palladacycle with the esteric carbonyl coordinated to the Pd center…”

Section: Introductionmentioning

confidence: 99%

Computational Overview of a Pd-Catalyzed Olefin Bis-alkoxycarbonylation Process

et al. 2020

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A comprehensive density functional theory analysis is reported for the one-pot bis-alkoxycarbonylation reaction of olefins to form succinic acid esters by action of the catalyst (N-N)Pd(TFA)2 (N-N = bis(2,6-dimethylphenyl)-2,3-dimethyl-1,4-diazabutadiene, TFA– = CF3CO2 –). The selective and efficient process involves alkene (H2C=CHR), CO, methanol, and p-benzoquinone (BQ) molecules as reactants. The catalytic mechanism, previously proposed on the basis of available experimental and literature data, is critically revised here. A plethora of optimized intermediates and transition states and their correlating energy profiles allow a step by step reconstruction of the entire cycle, highlighting key mechanistic aspects, such as the role of the R substituent in the olefin. One of its effects is determined by the presence of a 2e – donor group, which, depending on its power, may affect the catalysis up to its total inhibition. As another aspect, the key diester product forms through a reductive elimination step (Pd(II) → Pd(0) transformation) that excludes the previously proposed attainment of a Pd(II)–hydride complex. Finally, the paper illustrates the action of the sacrificial BQ oxidant in the restoration of the original Pd(II) catalyst, as found for other strictly related cases. The energy profile indicates that the rate-determining step occurs in the initial part of the reaction, given a +29.6 kcal mol–1 energy barrier, associated with a methoxo migration into an adjacent CO ligand. The result foreshadows a rather slow activation of the catalyst and a long duration of the cycle.

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“…For the dinuclear palladium aryloxides, Pd 2 L 2 (OAr) 2 (L = dmpm, dppm; Ar = Ph, OC 6 H 3 -2,6-Me), CO insertion predominantly occurs at the Pd−Pd bond, although the possibility of CO insertion into the Pd−O bond is also suggested . Methylpalladium(II) phenoxides, L 2 Pd(Me)(OPh) (L 2 = (PMe 3 ) 2 , dppe, tmeda, bpy), react with CO to produce phenyl acetate, MeCO 2 Ph . In this reaction, however, L 2 Pd(COMe)(OPh) rather than L 2 Pd(Me)(CO 2 Ph) is assumed to be the intermediate.…”

Section: Introductionmentioning

confidence: 99%

Reactivity of Diaryloxy Palladium Complex with TMEDA (N,N,N‘,N‘-Tetramethylethylenediamine) Ligand toward Carbon Monoxide and Carbon Dioxide

et al. 2002

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The reactivity of the diaryloxy palladium complex toward carbon monoxide was investigated relevant to the mechanism of the palladium-catalyzed oxidative carbonylation of phenol to produce diphenyl carbonate (DPC). (TMEDA)Pd(OC 6 H 4 -p-t-Bu) 2 (1) reacted at high CO pressures (10-80 atm) at 100 °C to give the di(p-tert-butyl)phenyl carbonate. The yield of the carbonate increased with the increase in the CO pressure and with the addition of triphenylphosphine. The 13 C{ 1 H} NMR and IR spectroscopic studies at room temperature under high CO pressure (50 atm) revealed that CO inserts into one of the Pd-O bonds in 1. Thus, the formation of palladium phenoxide followed by carbonylation and subsequent reductive elimination is considered to be one of the possible DPC formation routes in the oxidative carbonylation of phenol; the reductive elimination is slower than the carbonylation. The reactivity of 1 with carbon dioxide was also examined relating to the DPC synthesis from carbon dioxide and phenol. The reaction of 1 with CO 2 led to the formation of a palladium carbonate complex, (TMEDA)Pd(η 2 -CO 3 ) (2), whose molecular structure was determined by X-ray crystallography.

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Chemistry of diamino-ligated methylpalladium(II) alkoxides and aryloxides (Part II): methoxide formation and carbonylation reactions

Cited by 28 publications

References 63 publications

Theoretical Study of CO Migratory Insertion Reactions with Group 10 Metal−Alkyl and −Alkoxide Bonds

Theoretical Study of CO Migratory Insertion Reactions with Group 10 Metal−Alkyl and −Alkoxide Bonds

Computational Overview of a Pd-Catalyzed Olefin Bis-alkoxycarbonylation Process

Reactivity of Diaryloxy Palladium Complex with TMEDA (N,N,N‘,N‘-Tetramethylethylenediamine) Ligand toward Carbon Monoxide and Carbon Dioxide

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