Electron spin resonance and optical detection of manganese(IV) tetraphenylporphyrin

Konishi, Shiro; Hoshino, Mikio; Imamura, Masaki

doi:10.1021/j100220a017

Cited by 17 publications

(6 citation statements)

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“…The manganese porphyrin-catalyzed isocyanation reaction mixture (Figure a, red trace) contains similar features and g values (3.91, 2.01) as compared to both the authentic Mn IV (TMP)(NCO) 2 and the previously reported Mn IV (TPP)(NCO) 2 , which is consistent with the intermediacy of a Mn IV (TMP)(NCO) 2 complex during the isocyanation reaction. The spectral features at g = 3.91 and 2.01 are diagnostic of the existence of a high-spin, d 3 Mn IV species with an axially symmetric environment. , Hyperfine splitting of the I = 5/2 55 Mn nucleus of the catalyst is clear at g = 2.01, while the six small features at g = 3.91 can be resolved with derivatives (Figure S3).…”

Section: Resultsmentioning

confidence: 98%

Alkyl Isocyanates via Manganese-Catalyzed C–H Activation for the Preparation of Substituted Ureas

et al. 2017

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Organic isocyanates are versatile intermediates that provide access to a wide range of functionalities. In this work, we have developed the first synthetic method for preparing aliphatic isocyanates via direct C-H activation. This method proceeds efficiently at room temperature and can be applied to functionalize secondary, tertiary, and benzylic C-H bonds with good yields and functional group compatibility. Moreover, the isocyanate products can be readily converted to substituted ureas without isolation, demonstrating the synthetic potential of the method. To study the reaction mechanism, we have synthesized and characterized a rare Mn-NCO intermediate and demonstrated its ability to transfer the isocyanate moiety to alkyl radicals. Using EPR spectroscopy, we have directly observed a Mn intermediate under catalytic conditions. Isocyanation of celestolide with a chiral manganese salen catalyst followed by trapping with aniline afforded the urea product in 51% enantiomeric excess. This represents the only example of an asymmetric synthesis of an organic urea via C-H activation. When combined with our DFT calculations, these results clearly demonstrate that the C-NCO bond was formed through capture of a substrate radical by a Mn-NCO intermediate.

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Section: Resultsmentioning

confidence: 98%

Alkyl Isocyanates via Manganese-Catalyzed C–H Activation for the Preparation of Substituted Ureas

et al. 2017

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“…The six lines shown in Fig. 4c are a typical signal of Mn(IV) species, which indicates the catalytic process should involve high-valent oxo intermediate [42][43].…”

Section: In Situ Epr Spectra Study Of Cyclohexene Epoxidationmentioning

confidence: 97%

Biomimetic kinetics and mechanism of cyclohexene epoxidation catalyzed by metalloporphyrins

Zhou

2010

Chemical Engineering Journal

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“…Before this work, the roles of TPPMnCl and isobutyraldehyde have been well studied. As the literature reported, ,− it was suggested that the manganese porphyrin reacted with the aldehyde to generate an acyl radical at first, which was oxidized by O 2 generating acylperoxy radicals. Then the acylperoxy radical could act as a carrier by reacting with another aldehyde to give peroxyacid, thereby generating another acyl radical.…”

Section: Resultsmentioning

confidence: 98%

Tailoring Electronic Properties of Porphyrin Manganese on Boron Nitride for Enhancing Aerobic Oxidative Desulfurization at Room Temperature

Wei

Zhang

et al. 2019

ACS Sustainable Chem. Eng.

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Tailoring electronic properties of the central metal atom of metalloporphyrin has emerged as a practical approach to acquire a high catalytic performance. Herein, 5,10,15,20-tetraphenylporphyrin manganese chloride (TPPMnCl) was immobilized on hexagonal boron nitride (h-BN) and employed as a catalyst to achieve ultradeep aerobic oxidative desulfurization of diesel at room temperature. The interfacial electronic effect on the TPPMnCl induced by the h-BN was embraced, leading to an electron transfer from Mn to h-BN. The resulting high-valence Mn could facilitate the generation of reactive oxygen species from the reduction of oxygen. As a result, 99.2% of refractory aromatic sulfur removal for model diesel could be achieved at 30 °C using immobilized TPPMnCl and oxygen as the catalyst and oxidant, respectively. Besides, the catalytic mechanism was studied in detail, and the peroxyacid was found to be generated on the immobilized TPPMnCl as the active species. This study provides a strategy toward tailoring the electronic properties of TPPMnCl on h-BN for enhancing aerobic oxidative desulfurization at room temperature.

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Electron spin resonance and optical detection of manganese(IV) tetraphenylporphyrin

Cited by 17 publications

References 0 publications

Alkyl Isocyanates via Manganese-Catalyzed C–H Activation for the Preparation of Substituted Ureas

Alkyl Isocyanates via Manganese-Catalyzed C–H Activation for the Preparation of Substituted Ureas

Biomimetic kinetics and mechanism of cyclohexene epoxidation catalyzed by metalloporphyrins

Tailoring Electronic Properties of Porphyrin Manganese on Boron Nitride for Enhancing Aerobic Oxidative Desulfurization at Room Temperature

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