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Volumn 28, Issue 1, 2009, Pages 277-288

Reductive elimination and dissociative β-hydride abstraction from Pt(IV) hydroxide and methoxide complexes

Author keywords

[No Author keywords available]

Indexed keywords

HYDRIDE ABSTRACTIONS; HYDRIDE ELIMINATIONS; MECHANISTIC STUDIES; METAL CENTERS; REDUCTIVE ELIMINATIONS;

EID: 61849084100     PISSN: 02767333     EISSN: None     Source Type: Journal    
DOI: 10.1021/om800905q     Document Type: Article
Times cited : (80)

References (100)
  • 8
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    • Reference 1b, pp 170-175
    • Reference 1b, pp 170-175.
  • 18
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    • Matsunaga, P. T.; Mavropoulos, J. C.; Hillhouse, G. L. Polyhedron 1995, 14, 175. Note that the reductive elimination from Ni(II) is promoted by oxidants, and thus Ni(III) is likely involved in the reactions.
    • (a) Matsunaga, P. T.; Mavropoulos, J. C.; Hillhouse, G. L. Polyhedron 1995, 14, 175. Note that the reductive elimination from Ni(II) is promoted by oxidants, and thus Ni(III) is likely involved in the reactions.
  • 26
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    • Thompson, J. S, Randall, S. L, Atwood, J. D. Organometallics 1991, 10, 3906. See ref 5a for more information on this reaction
    • Thompson, J. S.; Randall, S. L.; Atwood, J. D. Organometallics 1991, 10, 3906. See ref 5a for more information on this reaction.
  • 35
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    • Reference la, p 90
    • Reference la, p 90.
  • 36
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    • Reference la, p 95
    • Reference la, p 95.
  • 41
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    • Based on a search of Pt(IV) hydroxide crystal structures in the Cambridge Structural Database using Conquest 1.8, Copyright CCDC 2006. Bruno, I. J.; Cole, J. C; Edgington, P. R.; Kessler, M.; Macrae, C. F.; McCabe, P.; Pearson, J.; Taylor, R. Acta Crystallogr. 2002, B58, 389.
    • Based on a search of Pt(IV) hydroxide crystal structures in the Cambridge Structural Database using Conquest 1.8, Copyright CCDC 2006. Bruno, I. J.; Cole, J. C; Edgington, P. R.; Kessler, M.; Macrae, C. F.; McCabe, P.; Pearson, J.; Taylor, R. Acta Crystallogr. 2002, B58, 389.
  • 45
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    • 3OH],) deducted from it.
    • 3OH],) deducted from it.
  • 49
    • 61849096013 scopus 로고    scopus 로고
    • As a result of the volatility of several of the organic species
    • As a result of the volatility of several of the organic species
  • 50
    • 61849150331 scopus 로고    scopus 로고
    • methane, ethane, etc, it is expected that some portion of these products is present in the headspace of the NMR tube, and therefore integrated yields are low estimates of the actual yields
    • (methane, ethane, etc.), it is expected that some portion of these products is present in the headspace of the NMR tube, and therefore integrated yields are low estimates of the actual yields.
  • 51
    • 61849152758 scopus 로고    scopus 로고
    • The presence of three minor unidentified products was indicated by the observation of three small singlets at 3.49 ppm (ca. 1, 4.68 ppm (0-5, and 5.25 ppm (0-3, Estimated yields of these unknown organic products (calculated on the assumption that the integral of each singlet represents three hydrogens) indicate that the contribution of these species to the overall product distribution is small
    • The presence of three minor unidentified products was indicated by the observation of three small singlets at 3.49 ppm (ca. 1%), 4.68 ppm (0-5%), and 5.25 ppm (0-3%). Estimated yields of these unknown organic products (calculated on the assumption that the integral of each singlet represents three hydrogens) indicate that the contribution of these species to the overall product distribution is small.
  • 52
    • 84868904626 scopus 로고    scopus 로고
    • 1H} NMR spectrum of this complex is comparable to those of other Pt(IV) (1080-1200 Hz), rather than Pt(II) (1700-1800 Hz), dppbz complexes, in which the phosphines are trans to methyl groups. No hydroxide signal was observed for 6;
    • 1H} NMR spectrum of this complex is comparable to those of other Pt(IV) (1080-1200 Hz), rather than Pt(II) (1700-1800 Hz), dppbz complexes, in which the phosphines are trans to methyl groups. No hydroxide signal was observed for 6;
  • 53
    • 61849086078 scopus 로고    scopus 로고
    • see Experimental Section for NMR characterization of 6.
    • see Experimental Section for NMR characterization of 6.
  • 54
    • 61849129931 scopus 로고    scopus 로고
    • In addition to the species listed in Table 3, two minor unidentified species showing singlets at 3.47 (0-3, and 3.27 (ca. 1, ppm in the 1H NMR spectrum were also evident. Estimated yields of these unknown organic products (calculated on the assumption that the integral of each singlet represents three hydrogens) indicate that the contribution of these species to the overall product distribution is small
    • 1H NMR spectrum were also evident. Estimated yields of these unknown organic products (calculated on the assumption that the integral of each singlet represents three hydrogens) indicate that the contribution of these species to the overall product distribution is small.
  • 55
    • 84868911450 scopus 로고    scopus 로고
    • Note that the total yield of organic products, including the estimates for the two unidentified species at 3.47 and 3.27, is 92 ± 9% (see refs 29 and 32). Methane is not included, as it is a byproduct of the formation of formaldehyde, methyl formate, and dimethyl carbonate (vide infra). The total Pt product yield is 100 ± 4%.
    • Note that the total yield of organic products, including the estimates for the two unidentified species at 3.47 and 3.27, is 92 ± 9% (see refs 29 and 32). Methane is not included, as it is a byproduct of the formation of formaldehyde, methyl formate, and dimethyl carbonate (vide infra). The total Pt product yield is 100 ± 4%.
  • 56
    • 84868895750 scopus 로고    scopus 로고
    • 1H} NMR spectra of these complexes are comparable to other Pt(IV) (1080-1200 Hz), rather than Pt(II) (1700-1800 Hz), dppbz complexes, in which the phosphines are trans to methyl groups.
    • 1H} NMR spectra of these complexes are comparable to other Pt(IV) (1080-1200 Hz), rather than Pt(II) (1700-1800 Hz), dppbz complexes, in which the phosphines are trans to methyl groups.
  • 58
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    • For a similar reaction at Ni(II) see ref 8b
    • (b) For a similar reaction at Ni(II) see ref 8b.
  • 59
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    • The presence of excess water in the fhermolyses of 1 also slightly increased the maximum observed yield of the unidentified transient Pt
    • The presence of excess water in the fhermolyses of 1 also slightly increased the maximum observed yield of the unidentified transient Pt
  • 60
    • 84868904627 scopus 로고    scopus 로고
    • IV species (6) from 2% to 5, Notably, it was shown in independent experiments that the addition of water to the Pt(IV) hydroxide complex 1 (5.7mM in C6D6) also resulted in the generation of species 6 at ambient temperature (80% conversion over 4 weeks).31 However, pure samples of 6 could not be isolated, which inhibited further characterization. The very slow formation of 6 (weeks at ambient temperature) argues against characterization of 6 as a simple hydrogen-bonded species 1 · H2O. A sample of 6 in THF was analyzed by ESI-MS and shows a signal at m/z, 1478 with an isotopic pattern indicative of two platinum atoms. The molar mass of a dimeric complex with the form of, dppbz)PtMe3(OH) · H 2O]2 would be 1443 g/mol
    • 2 would be 1443 g/mol.
  • 61
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    • In addition, two other trace organic products (4.68 ppm, 0-1, 5.25 ppm, 3-4%)30 were observed
    • 30 were observed.
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    • and references therein
    • Puddephatt, R. J. Coord. Chem. Rev. 2001, 219, 157, and references therein.
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    • Puddephatt, R.1    Coord, J.2
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    • A computational study of models of 8 and the related dppe system with different substituents on the phosphorous atoms proposed that phosphine dissociation may occur concurrently with C-H reductive elimination. Michel, C.; Laio, A.; Mohamed, F.; Krack, M.; Parrinello, M.; Milet, A. Organometallics 2007, 26, 1241.
    • A computational study of models of 8 and the related dppe system with different substituents on the phosphorous atoms proposed that phosphine dissociation may occur concurrently with C-H reductive elimination. Michel, C.; Laio, A.; Mohamed, F.; Krack, M.; Parrinello, M.; Milet, A. Organometallics 2007, 26, 1241.
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    • Acceleration of an O-H reductive elimination from a PdII
    • Acceleration of an O-H reductive elimination from a Pd(II)
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    • 2CR)(H) complex by protic additives was recently reported by Stahl and co-workers. Konnick, M. M.; Stahl, S. S. J. Am. Chem. Soc. 2008, 130, 5753.
    • 2CR)(H) complex by protic additives was recently reported by Stahl and co-workers. Konnick, M. M.; Stahl, S. S. J. Am. Chem. Soc. 2008, 130, 5753.
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    • Note that other examples (see ref 17b) are known in which water acts as the nucleophile. There is one other claim in the literature of direct C-O reductive elimination involving hydroxide,12 but later experiments by Hartwig and Mann on a related system5a have suggested that the reaction proceeds via nucleophilic attack of the iridium hydroxide group on methyl iodide and not a reductive elimination step
    • 5a have suggested that the reaction proceeds via nucleophilic attack of the iridium hydroxide group on methyl iodide and not a reductive elimination step.
  • 94
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    • Accurate integration of the signals for dimethoxymethane(δ 3.12 (s, 6H), δ 4.38 (s, 2H)) was not possible due to the very close proximity of other peaks.
    • Accurate integration of the signals for dimethoxymethane(δ 3.12 (s, 6H), δ 4.38 (s, 2H)) was not possible due to the very close proximity of other peaks.
  • 95
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    • 1H NMR spectroscopy. Walker, J. F. Formaldehyde: Chapman and Hall: New York, 1964.
    • 1H NMR spectroscopy. Walker, J. F. Formaldehyde: Chapman and Hall: New York, 1964.
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