In order to test the reliability of DFT methods for calculating electronic structures of [Fe(IV)O] system, detailed calculations of [Fe(IV)O](OH)2 models were performed for several low-energy states using multiconfiguration quasidegenerate perturbation theory (MCQDPT) as well as DFT-based methods. The minimum energy crossing points (MECP) of (5)A1/(5)B2 and (3)B2/(5)B2 were investigated based on Lagrange-Newton approach. The results show that M06 functional produce energy gaps close to those of MCQDPT results. Another topic in this article is that the electron configurations of [Fe(IV)O](OH)2 models strongly depend on the type of surface ligand used, and the two lowest states of these can facile transition each other by the MECP. The practicability of M06 method in locating the MECP is validated by the results of MCQDPT which demonstrate the two-state reactivity (TSR) can be studied with proper DFT method. These inspections provide the basis for further TSR study of larger [Fe(IV)O] system.
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http://dx.doi.org/10.1002/jcc.23535 | DOI Listing |
J Comput Chem
April 2014
Tianjin Key Laboratory of Structure and Performance for Functional Molecules, Key Laboratory of Inorganic-Organic Hybrid Functional Material Chemistry, Ministry of Education, College of Chemistry, Tianjin Normal University, 393 Bin Shui West Road, Tianjin, 300387, China.
In order to test the reliability of DFT methods for calculating electronic structures of [Fe(IV)O] system, detailed calculations of [Fe(IV)O](OH)2 models were performed for several low-energy states using multiconfiguration quasidegenerate perturbation theory (MCQDPT) as well as DFT-based methods. The minimum energy crossing points (MECP) of (5)A1/(5)B2 and (3)B2/(5)B2 were investigated based on Lagrange-Newton approach. The results show that M06 functional produce energy gaps close to those of MCQDPT results.
View Article and Find Full Text PDFPhys Chem Chem Phys
March 2012
Université de Lyon, Université Lyon 1 and CNRS, France.
Debate continues over which active species plays the role of oxidative agent during the Fenton reaction-the HO˙ radical or oxo iron [Fe(IV)O](2+). In this context, the present study investigates the oxidation of p-chlorophenol by [Fe(IV)O(H(2)O)(5)](2+) using DFT calculations, within gas-phase and micro-solvated models, in order to explore the possible role of oxo iron as a reactant. The results show that the chlorine atom substitution of p-chlorophenol by oxo iron is a highly stabilising step (ΔH = -83 kcal mol(-1)) with a free energy barrier of 5.
View Article and Find Full Text PDFJ Phys Chem A
December 2008
Laboratori de Simulació Computacional i Modelització (CoSMoLab), Parc Científic de Barcelona, Baldiri Reixac 10-12, 08028 Barcelona, Spain.
In catalases, the high redox intermediate known as compound I (Cpd I) is reduced back to the resting state by means of hydrogen peroxide in a 2-electron reaction [Cpd I (Por(*+)-Fe(IV)O) + H(2)O(2) --> Enz (Por-Fe(III)) + H(2)O + O(2)]. It has been proposed that this reaction takes place via proton transfer toward the distal His and hydride transfer toward the oxoferryl oxygen (H(+)/H(-) scheme) and some authors have related it to singlet oxygen generation. Here, we consider the possible reaction schemes and qualitatively analyze the electronic state of the species involved to show that the commonly used association of the H(+)/H(-) scheme with singlet oxygen production is not justified.
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