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Volumn 130, Issue 17, 2008, Pages 5753-5762

Reaction of molecular oxygen with a PdII-hydride to produce a PdII-hydroperoxide: Experimental evidence for an HX-reductive- elimination pathway

Author keywords

[No Author keywords available]

Indexed keywords

CATALYST ACTIVITY; NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY; OXIDATION; PALLADIUM COMPOUNDS;

EID: 42649133825     PISSN: 00027863     EISSN: None     Source Type: Journal    
DOI: 10.1021/ja7112504     Document Type: Article
Times cited : (153)

References (66)
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    • For reviews, see: (a) Stahl, S. S. Angew. Chem., Int. Ed. 2004, 43, 3400-3420.
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    • (b) Stahl, S. S. Science 2005, 309, 1824-1826.
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    • (i) Muzart, J. Tetrahedron 2003, 59, 5789-5816.
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    • For discussion and analysis of Pd decomposition during catalytic turnover, see
    • For discussion and analysis of Pd decomposition during catalytic turnover, see: Steinhoff, B. A.; Stahl, S. S. J. Am. Chem. Soc. 2006, 128, 4348-4355.
    • (2006) J. Am. Chem. Soc , vol.128 , pp. 4348-4355
    • Steinhoff, B.A.1    Stahl, S.S.2
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    • II, and the turnover-limiting step is associated with oxidation of the organic substrate. For leading references to mechanistic studies of reactions under catalytic conditions, see: (a) Mueller, J. A.; Goller, C. P.; Sigman, M. S. J. Am. Chem. Soc. 2004, 126, 9724-9734.
    • II, and the turnover-limiting step is associated with oxidation of the organic substrate. For leading references to mechanistic studies of reactions under catalytic conditions, see: (a) Mueller, J. A.; Goller, C. P.; Sigman, M. S. J. Am. Chem. Soc. 2004, 126, 9724-9734.
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    • 2, see: (a) Popp, B. V.; Stahl, S. S. In Organometallic Oxidation Catalysis; Meyer, F., Limberg, C., Eds.; Springer: New York, 2007; 22, pp 149-189.
    • 2, see: (a) Popp, B. V.; Stahl, S. S. In Organometallic Oxidation Catalysis; Meyer, F., Limberg, C., Eds.; Springer: New York, 2007; Vol. 22, pp 149-189.
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    • See, for example: a
    • See, for example: (a) Muzart, J.; Pete, J. P. J. Mol. Catal. 1982, 15, 373-376.
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    • Muzart, J.1    Pete, J.P.2
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    • Formation of metal-hydroperoxides via oxygenation of other transition-metal hydrides has been reported. Rhodium: (a) Roberts, H. L, Symes, W. R. J. Chem. Soc. A 1968, 1450-1453
    • Formation of metal-hydroperoxides via oxygenation of other transition-metal hydrides has been reported. Rhodium: (a) Roberts, H. L.; Symes, W. R. J. Chem. Soc. A 1968, 1450-1453.
  • 42
  • 55
    • 42649108531 scopus 로고    scopus 로고
    • The PdII-OOH complex 2 has been prepared independently via protonolysis of (IMes)2PdIIη2-O 2, See ref 6b and Supporting Information for details
    • 2). See ref 6b and Supporting Information for details.
  • 56
    • 36248985268 scopus 로고    scopus 로고
    • See Supporting Information for further details. Analogous ligand oxidation has been observed previously for a cobalt-hydroperoxide complex (see ref 12m, In addition, ligand decomposition in Pd-catalyzed aerobic oxidation of alcohols has been proposed to proceed via the reaction of an (unobserved) hydroperoxide intermediate with a ligand benzylic methyl group: Conley, N. R, Labios, L. A, Pearson, D. M, McCrory, C. C. L, Waymouth, R. M Organometallics 2007, 26, 5447-5453
    • See Supporting Information for further details. Analogous ligand oxidation has been observed previously for a cobalt-hydroperoxide complex (see ref 12m). In addition, ligand decomposition in Pd-catalyzed aerobic oxidation of alcohols has been proposed to proceed via the reaction of an (unobserved) hydroperoxide intermediate with a ligand benzylic methyl group: Conley, N. R.; Labios, L. A.; Pearson, D. M.; McCrory, C. C. L.; Waymouth, R. M Organometallics 2007, 26, 5447-5453.
  • 57
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    • In our preliminary communication of the reaction between 1 and O2 (ref 10, we reported clean, first-order kinetics for the oxygenation of 1 in the absence of additives. In subsequent studies, however, we determined that our original Pd-hydride samples contained trace amounts of BzOH that slightly increase the rate of the oxygenation reaction and result in clean, exponential kinetics. The BzOH originates from the synthesis of 1 and is not readily detected by NMR spectroscopy because it equilibrates with the BzO- ligand coordinated to Pd see Discussion later in this paper, In order to avoid this complication, subsequent syntheses of 1 were performed with a slight deficiency of BzOH relative to the Pd0 precursor
    • 0 precursor.
  • 58
    • 42649090580 scopus 로고    scopus 로고
    • 4OBz and BzOH; see previous section for details) or at low benzoate concentrations; in these cases, initial rate data were used.
    • 4OBz and BzOH; see previous section for details) or at low benzoate concentrations; in these cases, initial rate data were used.
  • 59
    • 4544248275 scopus 로고    scopus 로고
    • 2 solubility and issues related to mass-transfer into solution, see: (a) Steinhoff, B. A.; Guzei, I. A.; Stahl, S. S J. Am. Chem. Soc. 2004, 126, 11268-11278.
    • 2 solubility and issues related to mass-transfer into solution, see: (a) Steinhoff, B. A.; Guzei, I. A.; Stahl, S. S J. Am. Chem. Soc. 2004, 126, 11268-11278.
  • 61
    • 42649083789 scopus 로고    scopus 로고
    • 2). These empirical observations suggest that both radical and non-radical pathways might be involved.
    • 2). These empirical observations suggest that both radical and non-radical pathways might be involved.
  • 62
    • 42649104919 scopus 로고    scopus 로고
    • 2 and the Pd-hydride complex.
    • 2 and the Pd-hydride complex.
  • 63
    • 42649103121 scopus 로고    scopus 로고
    • A concerted reductive-elimination pathway has been identified by DFT calculations (see ref 16 and the discussion below), and the computations support a small isotope effect for this pathway. The calculated kinetic isotope effect for reductive elimination of acetic acid from a closely related model complex is 1.6. Popp, B. V.; Stahl, S. S., unpublished results.
    • A concerted reductive-elimination pathway has been identified by DFT calculations (see ref 16 and the discussion below), and the computations support a small isotope effect for this pathway. The calculated kinetic isotope effect for reductive elimination of acetic acid from a closely related model complex is 1.6. Popp, B. V.; Stahl, S. S., unpublished results.
  • 65
    • 42649111448 scopus 로고    scopus 로고
    • 2 is lower by 6.4 kcal/mol when the hydride ligand is trans to a methyl group rather than a carboxylate ligand.
    • 2 is lower by 6.4 kcal/mol when the hydride ligand is trans to a methyl group rather than a carboxylate ligand.


* 이 정보는 Elsevier사의 SCOPUS DB에서 KISTI가 분석하여 추출한 것입니다.