Abstract
We have investigated the reaction pathways for the primary hydroxylation reaction of trimethylmethane by a high-valent Fe(IV)=O porphyrin π-cation radical species known as compound I at the B3LYP/CEP-31G level. The isoelectronic analogy of the Fe(IV)=O core of compound I to a molecular oxygen (O2) has been successfully used to clarify the important roles of the singlet excited state of the Fe(IV)=O core in the alkane hydroxylation, which has hitherto been neglected. The reaction is initiated by the rate-determining hydrogen-atom abstraction from the substrate to give a discrete radical intermediate complex, in accordance with the conventional radical rebound mechanism. Similar to the chemistry of O2, however, one of the singlet excited states, i.e., the diradical component of the 1Δ state of the Fe(TV)=O core intercepts the triplet ground state (the 3Σ state) in the region of the transition state for the hydrogen abstraction. Our findings strongly indicate that the exchange polarization or intersystem crossing for the nonradiative transition to the locally singlet state is highly important to enhance the reactivity of compound I.
| Original language | English |
|---|---|
| Pages (from-to) | 2991-3009 |
| Number of pages | 19 |
| Journal | International Journal of Quantum Chemistry |
| Volume | 108 |
| Issue number | 15 |
| DOIs | |
| Publication status | Published - 2008 |
| Externally published | Yes |
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Keywords
- Compound I
- Density-functional theory
- Hydroxylation reaction
- Nonradiative transition
- P450
ASJC Scopus subject areas
- Condensed Matter Physics
- Atomic and Molecular Physics, and Optics
- Physical and Theoretical Chemistry
Cite this
Extended hartree-fock theory of chemical reactions. VIII. hydroxylation reactions by P450. / Isobe, Hiroshi; Nishihara, Satomichi; Shoji, Mitsuo; Yamanaka, Shusuke; Shimada, Jiro; Hagiwara, Masayuki; Yamaguchi, Kizashi.
In: International Journal of Quantum Chemistry, Vol. 108, No. 15, 2008, p. 2991-3009.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Extended hartree-fock theory of chemical reactions. VIII. hydroxylation reactions by P450
AU - Isobe, Hiroshi
AU - Nishihara, Satomichi
AU - Shoji, Mitsuo
AU - Yamanaka, Shusuke
AU - Shimada, Jiro
AU - Hagiwara, Masayuki
AU - Yamaguchi, Kizashi
PY - 2008
Y1 - 2008
N2 - We have investigated the reaction pathways for the primary hydroxylation reaction of trimethylmethane by a high-valent Fe(IV)=O porphyrin π-cation radical species known as compound I at the B3LYP/CEP-31G level. The isoelectronic analogy of the Fe(IV)=O core of compound I to a molecular oxygen (O2) has been successfully used to clarify the important roles of the singlet excited state of the Fe(IV)=O core in the alkane hydroxylation, which has hitherto been neglected. The reaction is initiated by the rate-determining hydrogen-atom abstraction from the substrate to give a discrete radical intermediate complex, in accordance with the conventional radical rebound mechanism. Similar to the chemistry of O2, however, one of the singlet excited states, i.e., the diradical component of the 1Δ state of the Fe(TV)=O core intercepts the triplet ground state (the 3Σ state) in the region of the transition state for the hydrogen abstraction. Our findings strongly indicate that the exchange polarization or intersystem crossing for the nonradiative transition to the locally singlet state is highly important to enhance the reactivity of compound I.
AB - We have investigated the reaction pathways for the primary hydroxylation reaction of trimethylmethane by a high-valent Fe(IV)=O porphyrin π-cation radical species known as compound I at the B3LYP/CEP-31G level. The isoelectronic analogy of the Fe(IV)=O core of compound I to a molecular oxygen (O2) has been successfully used to clarify the important roles of the singlet excited state of the Fe(IV)=O core in the alkane hydroxylation, which has hitherto been neglected. The reaction is initiated by the rate-determining hydrogen-atom abstraction from the substrate to give a discrete radical intermediate complex, in accordance with the conventional radical rebound mechanism. Similar to the chemistry of O2, however, one of the singlet excited states, i.e., the diradical component of the 1Δ state of the Fe(TV)=O core intercepts the triplet ground state (the 3Σ state) in the region of the transition state for the hydrogen abstraction. Our findings strongly indicate that the exchange polarization or intersystem crossing for the nonradiative transition to the locally singlet state is highly important to enhance the reactivity of compound I.
KW - Compound I
KW - Density-functional theory
KW - Hydroxylation reaction
KW - Nonradiative transition
KW - P450
UR - http://www.scopus.com/inward/record.url?scp=55349094691&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=55349094691&partnerID=8YFLogxK
U2 - 10.1002/qua.21874
DO - 10.1002/qua.21874
M3 - Article
AN - SCOPUS:55349094691
VL - 108
SP - 2991
EP - 3009
JO - International Journal of Quantum Chemistry
JF - International Journal of Quantum Chemistry
SN - 0020-7608
IS - 15
ER -