Issue 1, 2012

Mechanism of benzenehydroxylation by high-valent bare Feiv[double bond, length as m-dash]O2+: explicit electronic structure analysis

Abstract

The conversion of benzene to phenol by high-valent bare FeO2+ was comprehensively explored using a density functional theory method. The conductor-like screen model (COSMO) was used to mimic the role of solvent effect with acetonitrile chosen as the solvent. Two radical mechanisms and one oxygen insertion mechanism were tested for this conversion. The first radical mechanism can also be named as the concerted mechanism in which the hydrogen-atom abstraction process is accomplished via a four-centered transition state. The second radical mechanism is initiated by a direct hydrogen-atom abstraction with a collinear C–H–O transition structure. It is actually the same as the well-accepted rebound mechanism for the C–H bond activation by heme and nonheme iron-oxo catalysts. The third is an oxygen insertion mechanism which is essentially an aromatic electrophilic attack leading to an arenium σ-complex intermediate. The formation of a precomplex with an η4 coordinate environment in the first radical mechanism is energetically more favorable. However, the relatively lower activation energy barrier of the oxygen insertion mechanism compared to the radical ones makes it highly competitive if the Fe[double bond, length as m-dash]O2+ collides with benzene in the proper orientation. The detailed potential energy surfaces also indicate that the second radical mechanism, i.e., the benzene C–H bond activation through the rebound mechanism, is less favorable. This thorough theoretical study, especially the electronic structure analysis, may offer very important clues for understanding and studying C–H bond activation by iron-based catalysts and enzymatic reactions in protein active pockets.

Graphical abstract: Mechanism of benzene hydroxylation by high-valent bare Feiv [[double bond, length as m-dash]] O2+: explicit electronic structure analysis

Article information

Article type
Paper
Submitted
03 Jul 2011
Accepted
14 Oct 2011
First published
09 Nov 2011

Phys. Chem. Chem. Phys., 2012,14, 246-256

Mechanism of benzene hydroxylation by high-valent bare FeIV[double bond, length as m-dash]O2+: explicit electronic structure analysis

J. Li, X. Zhang and X. Huang, Phys. Chem. Chem. Phys., 2012, 14, 246 DOI: 10.1039/C1CP22187F

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements