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Modeling the cis-Oxo-Labile Binding Site Motif of Non-Heme Iron Oxygenases: Water Exchange and Oxidation Reactivity of a Non-Heme Iron(IV)-Oxo Compound Bearing a Tripodal Tetradentate Ligand

The spectroscopic and chemical characterization of a new synthetic non-heme iron(IV)-oxo species [FeIV(O)(Me,HPytacn)(S)]2+ (2, Me,HPytacn=1-(2′-pyridylmethyl)-4,7-dimethyl-1,4,7-triazacyclononane, S=CH3CN or H2O) is described. Complex 2 was prepared by reaction of [FeII(CF3SO3)2(Me,HPytacn)] (1) with peracetic acid. Complex 2 bears a tetradentate N4 ligand that leaves two cis sites available for binding an oxo group and a second external ligand but, unlike the related iron(IV)-oxo species with tetradentate ligands, it is remarkably stable at room temperature (t1/2>2 h at 288 K). Its ability to exchange the oxygen atom of the oxo ligand with water has been analyzed in detail by means of kinetic studies, and a mechanism is proposed on the basis of DFT calculations. Hydrogen-atom abstraction from C[BOND]H bonds and oxygen-atom transfer to sulfides by 2 have also been studied. Despite its thermal stability, 2 proves to be a very powerful oxidant that is capable of breaking the strong C[BOND]H bond of cyclohexane (bond dissociation energy=99.3 kcal mol−1)

Financial support for this work was provided by MEC-Spain (Projects CTQ2009–08464/BQU and CTQ2008–06696/BQU), and the US National Institutes of Health (GM-33162 to L.Q. and EB-001475 to E.M.). M.C. acknowledges Generalitat de Catalunya for an ICREA-Academia Award and SGR 2009 SGR 637. A.C., I. P., and M.G. thank MEC for FPU PhD grants. We thank RahuCat for a generous gift of tritosyl tacn. We thank W. Han and L. Noodleman for providing the utility programs to compute the Mçssbauer parameters of the iron complexes and M. Swart for his useful comments about the Mçssbauer calculations

© Chemistry-A European Journal, 2011, vol. 17, núm. 5, p. 1622-1634

Wiley-VCH Verlag

Author: Company Casadevall, Anna
Prat Casellas, Irene
Frisch, Jonathan R.
Mas-Ballesté, Rubén
Güell Serra, Mireia
Juhász, Gergely
Ribas Salamaña, Xavi
Münck, Eckard
Luis Luis, Josep Maria
Que, Lawrence
Costas Salgueiro, Miquel
Date: 2011
Abstract: The spectroscopic and chemical characterization of a new synthetic non-heme iron(IV)-oxo species [FeIV(O)(Me,HPytacn)(S)]2+ (2, Me,HPytacn=1-(2′-pyridylmethyl)-4,7-dimethyl-1,4,7-triazacyclononane, S=CH3CN or H2O) is described. Complex 2 was prepared by reaction of [FeII(CF3SO3)2(Me,HPytacn)] (1) with peracetic acid. Complex 2 bears a tetradentate N4 ligand that leaves two cis sites available for binding an oxo group and a second external ligand but, unlike the related iron(IV)-oxo species with tetradentate ligands, it is remarkably stable at room temperature (t1/2>2 h at 288 K). Its ability to exchange the oxygen atom of the oxo ligand with water has been analyzed in detail by means of kinetic studies, and a mechanism is proposed on the basis of DFT calculations. Hydrogen-atom abstraction from C[BOND]H bonds and oxygen-atom transfer to sulfides by 2 have also been studied. Despite its thermal stability, 2 proves to be a very powerful oxidant that is capable of breaking the strong C[BOND]H bond of cyclohexane (bond dissociation energy=99.3 kcal mol−1)
Financial support for this work was provided by MEC-Spain (Projects CTQ2009–08464/BQU and CTQ2008–06696/BQU), and the US National Institutes of Health (GM-33162 to L.Q. and EB-001475 to E.M.). M.C. acknowledges Generalitat de Catalunya for an ICREA-Academia Award and SGR 2009 SGR 637. A.C., I. P., and M.G. thank MEC for FPU PhD grants. We thank RahuCat for a generous gift of tritosyl tacn. We thank W. Han and L. Noodleman for providing the utility programs to compute the Mçssbauer parameters of the iron complexes and M. Swart for his useful comments about the Mçssbauer calculations
Format: application/pdf
ISSN: 0947-6539 (versió paper)
1521-3765 (versió electrònica)
Other identifiers: http://10.1002/chem.201002297
Document access: http://hdl.handle.net/10256/12251
Language: eng
Publisher: Wiley-VCH Verlag
Collection: MICINN/PN 2010-2012/CTQ2009-08464
MEC/PN 2009-2011/CTQ2008-06696
AGAUR/2009-2014/2009 SGR-637
Reproducció digital del document publicat a: http://10.1002/chem.201002297
Articles publicats (D-Q)
Is part of: © Chemistry-A European Journal, 2011, vol. 17, núm. 5, p. 1622-1634
Rights: Tots els drets reservats
Subject: Oxigenases
Oxygenases
Química bioinorgànica
Bioinorganic chemistry
Mecanismes de reacció (Química)
Reaction mechanisms (Chemistry)
Ferro
Iron
Title: Modeling the cis-Oxo-Labile Binding Site Motif of Non-Heme Iron Oxygenases: Water Exchange and Oxidation Reactivity of a Non-Heme Iron(IV)-Oxo Compound Bearing a Tripodal Tetradentate Ligand
Type: info:eu-repo/semantics/article
Repository: DUGiDocs

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