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Unraveling the mechanism of the manganese-salen epoxidation

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Abstract
Chiral salen-type complexes are valuable catalysts for the antioselective epoxidation of unfunctionlized olefins. The mechanism of this reaction with the manganese-salen complex has always been the subject of an intense debate [1, 2]. The originally proposed mechanism featuring a radical intermediate seems to fail in explaining several experimental observations[3] and various alternatives have been proposed. However the obtained results were highly dependent of the chosen methodology. We will present a methodological study comparing a broad range of DFT functionals with high-level CASSCF calculations [4]. An OPBE functional was shown to be the most performant. Using this functional it is confirmed that the mechanism featuring a radical intermediate is indeed the most likely. Moreover it makes it possible to explain the experimental observations that did not fit in the classical model. For example olefins with a cyclopropane moiety next to the double bound result in a mixture of epoxides and ringopening products depending on the exact reaction conditions. Our calculations show that a radical reaction intermediate can lead to the observed product distribution. This methodology can thus prove to give more insights in the mechanism of this interesting catalyst, allowing it to be optimized further for numerous applications.

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MLA
Bogaerts, Thomas et al. “Unraveling the Mechanism of the Manganese-salen Epoxidation.” Netherlands Catalysis & Chemistry Conference, Abstracts. 2014. 151–151. Print.
APA
Bogaerts, T., Van Yperen-De Deyne, A., Wouters, S., Van Neck, D., Van Der Voort, P., & Van Speybroeck, V. (2014). Unraveling the mechanism of the manganese-salen epoxidation. Netherlands Catalysis & Chemistry Conference, Abstracts (pp. 151–151). Presented at the Netherlands Catalysis & Chemistry Conference.
Chicago author-date
Bogaerts, Thomas, Andy Van Yperen-De Deyne, Sebastian Wouters, Dimitri Van Neck, Pascal Van Der Voort, and Veronique Van Speybroeck. 2014. “Unraveling the Mechanism of the Manganese-salen Epoxidation.” In Netherlands Catalysis & Chemistry Conference, Abstracts, 151–151.
Chicago author-date (all authors)
Bogaerts, Thomas, Andy Van Yperen-De Deyne, Sebastian Wouters, Dimitri Van Neck, Pascal Van Der Voort, and Veronique Van Speybroeck. 2014. “Unraveling the Mechanism of the Manganese-salen Epoxidation.” In Netherlands Catalysis & Chemistry Conference, Abstracts, 151–151.
Vancouver
1.
Bogaerts T, Van Yperen-De Deyne A, Wouters S, Van Neck D, Van Der Voort P, Van Speybroeck V. Unraveling the mechanism of the manganese-salen epoxidation. Netherlands Catalysis & Chemistry Conference, Abstracts. 2014. p. 151–151.
IEEE
[1]
T. Bogaerts, A. Van Yperen-De Deyne, S. Wouters, D. Van Neck, P. Van Der Voort, and V. Van Speybroeck, “Unraveling the mechanism of the manganese-salen epoxidation,” in Netherlands Catalysis & Chemistry Conference, Abstracts, Noordwijkerhout, the Netherlands, 2014, pp. 151–151.
@inproceedings{4339545,
  abstract     = {Chiral salen-type complexes are valuable catalysts for the antioselective epoxidation of unfunctionlized  olefins.  The  mechanism of  this reaction  with  the  manganese-salen complex has always been the subject of an intense debate  [1,  2]. The originally proposed mechanism  featuring  a radical  intermediate  seems  to  fail  in explaining  several experimental observations[3]  and various alternatives have been proposed. However the obtained results were highly dependent of the chosen methodology. We  will  present  a  methodological  study  comparing  a  broad  range  of  DFT  functionals with high-level CASSCF calculations [4]. An OPBE functional was shown to be the most performant. Using this functional it is confirmed that the mechanism featuring a radical intermediate  is indeed  the  most  likely.  Moreover  it  makes  it  possible  to  explain  the experimental observations that did not fit in the classical model. For example olefins with a cyclopropane moiety next to the double bound result in a mixture of epoxides and ringopening products depending on the exact reaction conditions. Our calculations show that a  radical  reaction  intermediate  can  lead  to  the  observed  product distribution.  This methodology can thus prove to give more insights in the mechanism of this interesting catalyst, allowing it to be optimized further for numerous applications.},
  author       = {Bogaerts, Thomas and Van Yperen-De Deyne, Andy and Wouters, Sebastian and Van Neck, Dimitri and Van Der Voort, Pascal and Van Speybroeck, Veronique},
  booktitle    = {Netherlands Catalysis & Chemistry Conference, Abstracts},
  language     = {eng},
  location     = {Noordwijkerhout, the Netherlands},
  pages        = {151--151},
  title        = {Unraveling the mechanism of the manganese-salen epoxidation},
  year         = {2014},
}