Abstract
Recently, it was shown that μ-oxo-μ-peroxodiiron(III) is converted to high-spin μ-oxodioxodiiron(IV) through O-O bond scission. Herein, the formation and high reactivity of the anti-dioxo form of high-spin μ-oxodioxodiiron(IV) as the active oxidant are demonstrated on the basis of resonance Raman and electronic-absorption spectral changes, detailed kinetic studies, DFT calculations, activation parameters, kinetic isotope effects (KIE), and catalytic oxidation of alkanes. Decay of μ-oxodioxodiiron(IV) was greatly accelerated on addition of substrate. The reactivity order of substrates is toluene<ethylbenzene≈cumene<trans-β-methylstyrene. The rate constants increased proportionally to the substrate concentration at low substrate concentration. At high substrate concentration, however, the rate constants converge to the same value regardless of the kind of substrate. This is explained by a two-step mechanism in which anti-μ-oxodioxodiiron(IV) is formed by syn-to-anti transformation of the syn-dioxo form and reacts with substrates as the oxidant. The anti-dioxo form is 620 times more reactive in the C-H bond cleavage of ethylbenzene than the most reactive diiron system reported so far. The KIE for the reaction with toluene/[D8]toluene is 95 at -30 °C, which the largest in diiron systems reported so far. The present diiron complex efficiently catalyzes the oxidation of various alkanes with H2O2. Strong anti oxidant: A high-spin μ-oxodioxodiiron(IV) species undergoes transformation from the syn-dioxo to the anti-dioxo form, which cleaves strong C-H bonds of alkanes. The high-spin anti-dioxodiiron(IV) species with a sterically less hindered structure (see figure) is a highly reactive and selective oxidant. These results provide insight into the high reactivity of the active species Q of soluble methane monooxygenases and the development of efficient alkane oxidation catalysts.
| Original language | English |
|---|---|
| Pages (from-to) | 5924-5936 |
| Number of pages | 13 |
| Journal | Chemistry - A European Journal |
| Volume | 22 |
| Issue number | 17 |
| DOIs | |
| Publication status | Published - Apr 18 2016 |
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All Science Journal Classification (ASJC) codes
- Catalysis
- Organic Chemistry
Cite this
Formation and High Reactivity of the anti-Dioxo Form of High-Spin μ-Oxodioxodiiron(IV) as the Active Species That Cleaves Strong C-H Bonds. / Kodera, Masahito; Ishiga, Shin; Tsuji, Tomokazu; Sakurai, Katsutoshi; Hitomi, Yutaka; Shiota, Yoshihito; Sajith, P. K.; Yoshizawa, Kazunari; Mieda, Kaoru; Ogura, Takashi.
In: Chemistry - A European Journal, Vol. 22, No. 17, 18.04.2016, p. 5924-5936.Research output: Contribution to journal › Article
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TY - JOUR
T1 - Formation and High Reactivity of the anti-Dioxo Form of High-Spin μ-Oxodioxodiiron(IV) as the Active Species That Cleaves Strong C-H Bonds
AU - Kodera, Masahito
AU - Ishiga, Shin
AU - Tsuji, Tomokazu
AU - Sakurai, Katsutoshi
AU - Hitomi, Yutaka
AU - Shiota, Yoshihito
AU - Sajith, P. K.
AU - Yoshizawa, Kazunari
AU - Mieda, Kaoru
AU - Ogura, Takashi
PY - 2016/4/18
Y1 - 2016/4/18
N2 - Recently, it was shown that μ-oxo-μ-peroxodiiron(III) is converted to high-spin μ-oxodioxodiiron(IV) through O-O bond scission. Herein, the formation and high reactivity of the anti-dioxo form of high-spin μ-oxodioxodiiron(IV) as the active oxidant are demonstrated on the basis of resonance Raman and electronic-absorption spectral changes, detailed kinetic studies, DFT calculations, activation parameters, kinetic isotope effects (KIE), and catalytic oxidation of alkanes. Decay of μ-oxodioxodiiron(IV) was greatly accelerated on addition of substrate. The reactivity order of substrates is toluene8]toluene is 95 at -30 °C, which the largest in diiron systems reported so far. The present diiron complex efficiently catalyzes the oxidation of various alkanes with H2O2. Strong anti oxidant: A high-spin μ-oxodioxodiiron(IV) species undergoes transformation from the syn-dioxo to the anti-dioxo form, which cleaves strong C-H bonds of alkanes. The high-spin anti-dioxodiiron(IV) species with a sterically less hindered structure (see figure) is a highly reactive and selective oxidant. These results provide insight into the high reactivity of the active species Q of soluble methane monooxygenases and the development of efficient alkane oxidation catalysts.
AB - Recently, it was shown that μ-oxo-μ-peroxodiiron(III) is converted to high-spin μ-oxodioxodiiron(IV) through O-O bond scission. Herein, the formation and high reactivity of the anti-dioxo form of high-spin μ-oxodioxodiiron(IV) as the active oxidant are demonstrated on the basis of resonance Raman and electronic-absorption spectral changes, detailed kinetic studies, DFT calculations, activation parameters, kinetic isotope effects (KIE), and catalytic oxidation of alkanes. Decay of μ-oxodioxodiiron(IV) was greatly accelerated on addition of substrate. The reactivity order of substrates is toluene8]toluene is 95 at -30 °C, which the largest in diiron systems reported so far. The present diiron complex efficiently catalyzes the oxidation of various alkanes with H2O2. Strong anti oxidant: A high-spin μ-oxodioxodiiron(IV) species undergoes transformation from the syn-dioxo to the anti-dioxo form, which cleaves strong C-H bonds of alkanes. The high-spin anti-dioxodiiron(IV) species with a sterically less hindered structure (see figure) is a highly reactive and selective oxidant. These results provide insight into the high reactivity of the active species Q of soluble methane monooxygenases and the development of efficient alkane oxidation catalysts.
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U2 - 10.1002/chem.201600048
DO - 10.1002/chem.201600048
M3 - Article
VL - 22
SP - 5924
EP - 5936
JO - Chemistry - A European Journal
JF - Chemistry - A European Journal
SN - 0947-6539
IS - 17
ER -