Non-redox metal ion promoted oxygen transfer by a non-heme manganese catalyst

Chen, Zhuqi; Yang, Ling; Choe, Cholho; Lv, Zhanao; Yin, Guochuan

doi:10.1039/c4cc07981g

Cited by 52 publications

(40 citation statements)

References 36 publications

(6 reference statements)

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“…Clearly, the active intermediate for epoxidation in the presence of Al 3+ is different from that of using Mn(TPA)Cl 2 alone. 22 These electrochemical oxidation waves also indicate that TPA and BPMEN have similar electron donation ability and coordination structure around manganese(II) ions. Remarkably, there was no cis-stilbene epoxide formation.…”

Section: Resultsmentioning

confidence: 84%

“…Conversion of styrene was also promoted from 9.1% to 71.9%, and the yield of epoxystyrene increased to 45.1%. 22 This typical 16-line signal is highly characteristic of the mixed valent di-µ-oxobridged diamond core, Mn III -(µ-O) 2 -Mn IV , which has been reported in chemical oxidation or electrochemical process of various manganese(II) complexes. However, the required reaction time for electron-deficient linear olefins is much longer (8 h) than that of cyclo-olefins or electron-rich olefins (3.5 h), which leads to a lower selectivity because of Lewis-acid-catalyzed ring-opening of epoxide.…”

Section: Resultsmentioning

confidence: 86%

“…In our previous communication, 22 the interaction between Mn(IV) species and Al 3+ was described as Mn(IV)=O•••Al 3+ for which a similar, though controversial, structure has been illustrated in literature. [7][8][9] (Table 4).…”

Section: Resultsmentioning

confidence: 92%

“…of Al 3+ generated high oxidation activity with 91.3% conversion and 69.0% yield of epoxide. 22 The evidence to display their interaction first comes from EPR studies (Figure 2). Conversion of styrene was also promoted from 9.1% to 71.9%, and the yield of epoxystyrene increased to 45.1%.…”

Section: Resultsmentioning

confidence: 99%

“…18 This finding resembles the acceleration effect caused by binding Lewis acid to the active M n+ =O moieties as described above. 22 Herein, we report this remarkable promotional effect with manganese catalysts bearing different ligands, and the epoxidation mechanism has been discussed in details. 19,20 Moreover, the presence of Ca 2+ and Clcan synergistically affect the redox potentials of the manganese complexes, thus modulate their reactivity in oxidations, 21 which may provide new clues to understand their roles in oxygen evolution in Photosystem II.…”

Section: Introductionmentioning

confidence: 90%

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Redox-inactive metal ions promoted the catalytic reactivity of non-heme manganese complexes towards oxygen atom transfer

Choe

Yang

et al. 2015

Dalton Trans.

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Redox-inactive metal ions can modulate the reactivity of redox-active metal ions in a variety of biological and chemical oxidations. Many synthetic models have been developed to help address the elusive roles of these redox-inactive metal ions. Using a non-heme manganese(II) complex as the model, the influence of redox-inactive metal ions as a Lewis acid on its catalytic efficiency in oxygen atom transfer was investigated. In the absence of redox-inactive metal ions, the manganese(II) catalyst is very sluggish, for example, in cyclooctene epoxidation, providing only 9.9% conversion with 4.1% yield of epoxide. However, addition of 2 equiv. of Al(3+) to the manganese(II) catalyst sharply improves the epoxidation, providing up to 97.8% conversion with 91.4% yield of epoxide. EPR studies of the manganese(II) catalyst in the presence of an oxidant reveal a 16-line hyperfine structure centered at g = 2.0, clearly indicating the formation of a mixed valent di-μ-oxo-bridged diamond core, Mn(III)-(μ-O)2-Mn(IV). The presence of a Lewis acid like Al(3+) causes the dissociation of this diamond Mn(III)-(μ-O)2-Mn(IV) core to form monomeric manganese(iv) species which is responsible for improved epoxidation efficiency. This promotional effect has also been observed in other manganese complexes bearing various non-heme ligands. The findings presented here have provided a promising strategy to explore the catalytic reactivity of some di-μ-oxo-bridged complexes by adding non-redox metal ions to in situ dissociate those dimeric cores and may also provide clues to understand the mechanism of methane monooxygenase which has a similar diiron diamond core as the intermediate.

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Section: Resultsmentioning

confidence: 84%

Section: Resultsmentioning

confidence: 86%

Section: Resultsmentioning

confidence: 92%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 90%

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Redox-inactive metal ions promoted the catalytic reactivity of non-heme manganese complexes towards oxygen atom transfer

Choe

Yang

et al. 2015

Dalton Trans.

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Manganese‐Catalyzed Dihydroxylation and Epoxidation of Olefins

Eisink

Browne

2021

Manganese Catalysis in Organic Synthesis

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High‐Valent Oxomanganese Complexes of Relevance in Oxyfunctionalization of Hydrocarbons

Biswas¹,

Biswas²

2022

Handbook of CH-Functionalization

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Selective activation of inert and ubiquitous CH bonds is one of the most challenging reactions in synthetic organic chemistry. Nature utilizes earth‐abundant paramagnetic metals to bind molecular oxygen and forms reactive high‐valent metal–oxo intermediates, which in turn, cleave strong CH bonds. A large number of biomimetic metal–oxo transients have been successfully synthesized in the last few decades, and many of these have shown promising reactivity toward oxyfunctionalization of hydrocarbons. The field is largely dominated by iron and manganese complexes supported by heme or nonheme ligands. Manganese, albeit of little significance in biological oxidation reactions, can generate high‐valent oxo transients to achieve stoichiometric and catalytic CH and CC activation. Reactivity studies in tandem with spectroscopic and computational analyses have endowed important insights onto the energetics of the oxomanganese transients. Oxidative reactivity of the high‐valent oxomanganese complexes has been shown to be influenced by secondary interactions, redox potentials, and metal–oxo basicity In this article, we highlight notable advances made in the high‐valent oxomanganese chemistry, with special emphasis on their reactivity in oxidation reactions, which include hydroxylation of alkanes and epoxidation of olefins.

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Non-redox metal ion promoted oxygen transfer by a non-heme manganese catalyst

Cited by 52 publications

References 36 publications

Redox-inactive metal ions promoted the catalytic reactivity of non-heme manganese complexes towards oxygen atom transfer

Redox-inactive metal ions promoted the catalytic reactivity of non-heme manganese complexes towards oxygen atom transfer

Manganese‐Catalyzed Dihydroxylation and Epoxidation of Olefins

High‐Valent Oxomanganese Complexes of Relevance in Oxyfunctionalization of Hydrocarbons

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