Kinetics and mechanism of epoxidation of olefins by chiral tetrapyridyl oxoiron(IV) complex

Bashdar I. Meena, Dóra Lakk-Bogáth, Balázs Kripli, G. Speier, J. Kaizer

Research output: Contribution to journalArticle

4 Citations (Scopus)

Abstract

The reactivity of the previously reported low-spin (S = 1) oxoiron(IV) complex, [FeIV(asN4Py)(O)]2+ (2) with chiral pentadentate ligand, asN4Py (asN4Py = N,N-bis(2-pyridylmethyl)-1,2-di(2-pyridyl)ethylamine), has been investigated in the oxidation reaction of various alkenes such as cis-cyclooctene and styrene derivatives. A linear free-energy relationship between the second-order rate constants (k2) for the para-substituted styrene oxidations and the total substituent effect (TE) parameters has been established: ρTE [rad] = +0.19. A comparison of this correlation for the corresponding oxoruthenium(IV)-mediated epoxidation reactions has revealed that the oxidation of aromatic alkenes mediated by 2 proceeds via the rate-limiting formation of a benzylic radical intermediate in a nonconcerted process. Based on these results above, similar mechanism with radicaloid intermediates can be proposed for other cyclic and acyclic alkenes. The moderate enantioselectivities for the oxidation of styrene derivatives (8–12% ee) can be explained by the rotation/collapse processes through C–C bond of the radicaloid species before the epoxide ring closure.

Original languageEnglish
Pages (from-to)141-145
Number of pages5
JournalPolyhedron
Volume151
DOIs
Publication statusPublished - Sep 1 2018

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Keywords

  • Alkene epoxidation
  • Biomimetics
  • Enantioselectivity
  • Iron(IV)-oxo complex
  • Kinetics

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Inorganic Chemistry
  • Materials Chemistry

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