Tunneling of a hydrogen atom in low temperature processes

Трахтенберг, Л. И.; Klochikhin, V. L.; Pshezhetsky, S.Ya.

doi:10.1016/0301-0104(81)80099-7

Cited by 41 publications

(22 citation statements)

References 11 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This reaction has been studied experimentally at low temperature by various authors [4,. Previously, the authors [21] assumed a priori that the kinetic curves are exponential. Later, Doba et al [22] and Vyazovkin et al [23] observed that the decay of the methyl radical in methanol glass at low temperatures is nonexponential.…”

Section: Resultsmentioning

confidence: 99%

Temperature dependence of hydrogen transfer reactions via tunneling at low temperatures

Chandra

Rao

1993

Int J of Quantum Chemistry

View full text Add to dashboard Cite

In this paper, we present a symmetrical and adiabatic reaction path for hydrogen transfer from methane by methyl by an ab initio method using the 6-316" basis set with the M P~ corrections for u~F/6-316** optimized geometries. The theoretical barrier is fitted with the symmetric Eckart function. We, then, take thermal averages of the rate constant (k) considering the discrete nature of the C-H oscillators and the continuous character of the various low-frequency modes of the composite system. Finally, we present a linear relation between log k and temperature. It is shown that this relation gives a good description of the kinetic results of both thermal and photochemical H-transfer reactions in the region of low temperatures.

show abstract

Section: Resultsmentioning

confidence: 99%

Temperature dependence of hydrogen transfer reactions via tunneling at low temperatures

Chandra

Rao

1993

Int J of Quantum Chemistry

View full text Add to dashboard Cite

show abstract

“…The proton donor-acceptor mode is assumed to be harmonic with effective mass M and vibrational frequency Ω. In the derivations, the coupling is assumed to decrease exponentially with R : 8–9,72–74 …”

Section: Theoretical Concepts Of Hydrogen Tunnelingmentioning

confidence: 99%

Hydrogen Tunneling in Enzymes and Biomimetic Models

2013

View full text Add to dashboard Cite

“…If heavy atom motion closely tracks hydrogen transfer, then they move on the same time scale, and the transfer can be regarded as highly adiabatic. In contrast, if there exists a substantial part of the reaction coordinate that is described largely in terms of hydrogen motion, then the reaction can be regarded as being largely diabatic [15].…”

Section: The Physical Meaning Of Large Kiesmentioning

confidence: 99%

“…Hydrogen tunneling models that have been applied to modeling experimental data thus far focus on parameterizing most or all heavy atom motion, while the hydrogen transfer coordinate is treated as a special coordinate [15][16][17][18][19][20][21][22][23][24][25][26][27][28]. A primary detraction regarding these models is that the role of heavy atom motion is included in a semi-empirical sense.…”

Section: The Physical Meaning Of Large Kiesmentioning

confidence: 99%

“…The primary KIE for the hydrogen abstraction step in the SLO-catalyzed oxidation of linoleic acid is among the largest reported. Large KIEs are indicative of transfer distances which are on the order of the de Broglie wavelength or longer [15,23,29,30]. Such a situation implies that the rate is governed by configurations in which the overlap between the hydrogen donor and acceptor hydrogenic wavefunctions is small.…”

Section: The Physical Meaning Of Large Kiesmentioning

confidence: 99%

See 1 more Smart Citation

Modeling temperature dependent kinetic isotope effects for hydrogen transfer in a series of soybean lipoxygenase mutants: The effect of anharmonicity upon transfer distance

Meyer¹,

Klinman²

2005

Chemical Physics

View full text Add to dashboard Cite

Soybean lipoxygenase-1 (SLO) catalyzes the oxidation of linoleic acid. The rate-limiting step in this transformation is the net abstraction of the pro-S hydrogen atom from the center of the 1,5-pentadienyl moiety in linoleic acid. The large deuterium kinetic isotope effect (KIE) for this step appears in the first order rate constant ((D)k(cat) = 81 ± 5 at T = 25 °C). Furthermore, the KIE and the rate for protium abstraction are weakly temperature dependent (E(A,D) - E(A,H) = 0.9 ± 0.2 kcal/mol and E(A,H) = 2.1 ± 0.2 kcal/mol, respectively). Mutations at a hydrophobic site about 13 Å from the active site Fe(III), Ile(553), induce a marked temperature dependence that varies roughly in accordance with the degree to which the residue is changed in bulk from the wild type Ile. While the temperature dependence for these mutants varies from the wild type enzyme, the magnitude of the KIE at 25 °C is on the same order of magnitude. A hydrogen tunneling model [Kuznetsov, A.M., Ulstrup, J. Can. J. Chem. 77 (1999) 1085-1096] is utilized to model the KIE temperature profiles for the wild type SLO and each Ile(553) mutant. Hydrogenic wavefunctions are modeled using harmonic oscillators and Morse oscillators in order to explore the effects of anharmonicity upon computed kinetic observables used to characterize this hydrogen transfer.

show abstract

Tunneling of a hydrogen atom in low temperature processes

Cited by 41 publications

References 11 publications

Temperature dependence of hydrogen transfer reactions via tunneling at low temperatures

Temperature dependence of hydrogen transfer reactions via tunneling at low temperatures

Hydrogen Tunneling in Enzymes and Biomimetic Models

Modeling temperature dependent kinetic isotope effects for hydrogen transfer in a series of soybean lipoxygenase mutants: The effect of anharmonicity upon transfer distance

Contact Info

Product

Resources

About