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Volumn 124, Issue 38, 2002, Pages 11404-11416

On the mechanism of (PCP)Ir-catalyzed acceptorless dehydrogenation of alkanes: A combined computational and experimental study

Author keywords

[No Author keywords available]

Indexed keywords

PINCER COMPLEXES;

EID: 0037174388     PISSN: 00027863     EISSN: None     Source Type: Journal    
DOI: 10.1021/ja012460d     Document Type: Article
Times cited : (118)

References (72)
  • 30
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    • December, Honolulu; Abstract 90004907
    • Presented in part at the Pacifichem 2000 Congress, December, 2000, Honolulu; Abstract 90004907. A preliminary account of some of this work has also been communicated as ref 11.
    • (2000) Pacifichem 2000 Congress
  • 33
    • 2142710365 scopus 로고    scopus 로고
    • note
    • th + RT, and the Gibbs free energy is G = H - TS.
  • 34
    • 0028316720 scopus 로고
    • 2), which are particularly closely related to the nonclassical intermediates calculated in this work. Six values were determined for ΔS‡. ranging from 0.7 ± 1.0 to 3.7 ± 1.1 eu: (a) Hauger, B. E.; Gusev, D.; Caulton, K. G. J. Am. Chem. Soc. 1994, 116, 208-214.
    • (1994) J. Am. Chem. Soc. , vol.116 , pp. 208-214
    • Hauger, B.E.1    Gusev, D.2    Caulton, K.G.3
  • 37
    • 2142820241 scopus 로고    scopus 로고
    • note
    • H2elim. Extrapolating from the enthalpy difference in this case gives a free energy of 38.8 kcal/mol. The average of these two values. 37.4 kcal/mol, is shown in Figure 7. The basis for this estimation method is well established, particularly for related "seven-coordinate" iridium complexes (see ref 21).
  • 38
    • 2142648076 scopus 로고    scopus 로고
    • note
    • r-BuPCP)Ir(Ph)H (ref 9).
  • 39
    • 2142646698 scopus 로고    scopus 로고
    • note
    • 25,26
  • 42
    • 2142650929 scopus 로고    scopus 로고
    • note
    • -5 atm at 200°C.
  • 44
    • 0002654739 scopus 로고
    • For reviews of alkane C-H bond activation by organometallic complexes, see ref 1 and (a) Jones, W. D.; Feher, F. J. Acc. Chem. Res. 1989, 22, 91-100.
    • (1989) Acc. Chem. Res. , vol.22 , pp. 91-100
    • Jones, W.D.1    Feher, F.J.2
  • 47
    • 0001218371 scopus 로고
    • Some more recent papers that have addressed selectivity in particular and provide good lead references include: (d) Harper, T. G. P.; Desrosiers, P. J.; Flood, T. C. Organometallics 1990, 9, 2523-2528.
    • (1990) Organometallics , vol.9 , pp. 2523-2528
    • Harper, T.G.P.1    Desrosiers, P.J.2    Flood, T.C.3
  • 51
    • 2142758917 scopus 로고    scopus 로고
    • note
    • The relative differences in the addition rates among different alkane substrates for kinetic measurements are usually much smaller than those observed in the present case. This is probably because direct measurements of addition rates necessarily involve exothermic additions, whereas in the present case the rate-determining step is endothermic. Thus, the transition state is late and, perhaps more importantly, our kinetic barriers include a thermodynamic barrier. Thermodynamic variations among additions of various hydrocarbons are often found to be of the same order of magnitude as those in the present case.
  • 52
    • 0000410149 scopus 로고    scopus 로고
    • Most of the currently available functionals (including B3LYP) underestimate intermolecular binding energies and charge-transfer effects at long range. It is possible that the B3LYP functionals differentially overestimate the energies in metal complexes with high coordination numbers and in the transition states, which lead to the formation of these complexes. See, for example: (a) Paizs, B.; Suhai, S. J. Comput. Chem. 1998, 19, 575.
    • (1998) J. Comput. Chem. , vol.19 , pp. 575
    • Paizs, B.1    Suhai, S.2
  • 54
    • 2142714744 scopus 로고    scopus 로고
    • Ref 13
    • (c) Ref 13.
  • 56
    • 2142701682 scopus 로고    scopus 로고
    • note
    • 2(sol] for linear olefins at the concentrations monitored (> ca. 10 mM), but not for cyclooctene at concentrations in which the stirring rate was varied (< ca. 100 mM).
  • 57
    • 2142761835 scopus 로고    scopus 로고
    • note
    • I is reported to be approximately 18 kcal/mol lower in enthalpy than these final products (Table 1 of ref 13).
  • 69
    • 2142763227 scopus 로고    scopus 로고
    • note
    • 3, we find ΔΔE = -3.3 kcal/mol and ΔΔE‡ = -4.8 kcal/mol.


* 이 정보는 Elsevier사의 SCOPUS DB에서 KISTI가 분석하여 추출한 것입니다.