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Triggering the generation of an iron(IV)-oxo compound and its reactivity toward sulfides by RuII photocatalysis

The preparation of [FeIV(O)(MePy2tacn)]2+ (2, MePy2tacn = N-methyl-N,N-bis(2-picolyl)-1,4,7-triazacyclononane) by reaction of [FeII(MePy2tacn)(solvent)]2+ (1) and PhIO in CH3CN and its full characterization are described. This compound can also be prepared photochemically from its iron(II) precursor by irradiation at 447 nm in the presence of catalytic amounts of [Ru II(bpy)3]2+ as photosensitizer and a sacrificial electron acceptor (Na2S2O8). Remarkably, the rate of the reaction of the photochemically prepared compound 2 toward sulfides increases 150-fold under irradiation, and 2 is partially regenerated after the sulfide has been consumed; hence, the process can be repeated several times. The origin of this rate enhancement has been established by studying the reaction of chemically generated compound 2 with sulfides under different conditions, which demonstrated that both light and [Ru II(bpy)3]2+ are necessary for the observed increase in the reaction rate. A combination of nanosecond time-resolved absorption spectroscopy with laser pulse excitation and other mechanistic studies has led to the conclusion that an electron transfer mechanism is the most plausible explanation for the observed rate enhancement. According to this mechanism, the in-situ-generated [RuIII(bpy)3] 3+ oxidizes the sulfide to form the corresponding radical cation, which is eventually oxidized by 2 to the corresponding sulfoxide

We acknowledge the European Commission for projects FP7-PEOPLE-2011-CIG-303522 (A.C.), FP7-PEOPLE-2010-ERG-268445 (J.L.-F.), FP7-PEOPLE-CIG-303522 (M.G.B.), and ERC-009StG-239910 (MC.); the Spanish Ministry of Science for Projects CTQ2012-37420-C02-01/BQU (MC.), CSD2010-00065 (MC.), and CTQ2011-27758 (J.P.P.); Generalitat de Catalunya for an ICREA Academia Award and Project 2009-SGR637 (M.C.); and Generalitat Valenciana for Project ACOMP/2013/008 (J.P.P.). The Spanish Ministry of Science is acknowledged for a Ramon y Cajal contract to A.C. and J.L.-F. J.M.L. acknowledges the support, in part, of Labex ARCANE (ANR-11-LABX-0003-01). The work at the University of Minnesota was supported by the US National Science Foundation (Grant CHE1058248 to L.Q) and the Dr. Venkateswarlu Pothapragada and Family Fellowship (to M.P.). XAS data were collected at beamline 9-3 of the Stanford Synchrotron Radiation Lightsource supported by the US-NIH and US-DOE. We thank Catexel for a generous gift of tritosyl-1,4,7-triazacyclononane

© Journal of the American Chemical Society, 2014, vol. 136, p. 4624-4633

American Chemical Society (ACS)

Manager: Ministerio de Economía y Competitividad (Espanya)
Ministerio de Ciencia e Innovación (Espanya)
European Research Council
Generalitat de Catalunya. Agència de Gestió d’Ajuts Universitaris i de Recerca
Author: Company Casadevall, Anna
Sabeña Vila, Gerard
González Béjar, María
Gómez Martín, Laura
Clémancey, Martin
Blondin, Geneviève
Jasniewski, Andrew J.
Puri, Mayank
Browne, Wesley R.
Latour, Jean Marc
Que, Lawrence
Costas Salgueiro, Miquel
Pérez Prieto, Julia
Lloret Fillol, Julio
Date: 2014
Abstract: The preparation of [FeIV(O)(MePy2tacn)]2+ (2, MePy2tacn = N-methyl-N,N-bis(2-picolyl)-1,4,7-triazacyclononane) by reaction of [FeII(MePy2tacn)(solvent)]2+ (1) and PhIO in CH3CN and its full characterization are described. This compound can also be prepared photochemically from its iron(II) precursor by irradiation at 447 nm in the presence of catalytic amounts of [Ru II(bpy)3]2+ as photosensitizer and a sacrificial electron acceptor (Na2S2O8). Remarkably, the rate of the reaction of the photochemically prepared compound 2 toward sulfides increases 150-fold under irradiation, and 2 is partially regenerated after the sulfide has been consumed; hence, the process can be repeated several times. The origin of this rate enhancement has been established by studying the reaction of chemically generated compound 2 with sulfides under different conditions, which demonstrated that both light and [Ru II(bpy)3]2+ are necessary for the observed increase in the reaction rate. A combination of nanosecond time-resolved absorption spectroscopy with laser pulse excitation and other mechanistic studies has led to the conclusion that an electron transfer mechanism is the most plausible explanation for the observed rate enhancement. According to this mechanism, the in-situ-generated [RuIII(bpy)3] 3+ oxidizes the sulfide to form the corresponding radical cation, which is eventually oxidized by 2 to the corresponding sulfoxide
We acknowledge the European Commission for projects FP7-PEOPLE-2011-CIG-303522 (A.C.), FP7-PEOPLE-2010-ERG-268445 (J.L.-F.), FP7-PEOPLE-CIG-303522 (M.G.B.), and ERC-009StG-239910 (MC.); the Spanish Ministry of Science for Projects CTQ2012-37420-C02-01/BQU (MC.), CSD2010-00065 (MC.), and CTQ2011-27758 (J.P.P.); Generalitat de Catalunya for an ICREA Academia Award and Project 2009-SGR637 (M.C.); and Generalitat Valenciana for Project ACOMP/2013/008 (J.P.P.). The Spanish Ministry of Science is acknowledged for a Ramon y Cajal contract to A.C. and J.L.-F. J.M.L. acknowledges the support, in part, of Labex ARCANE (ANR-11-LABX-0003-01). The work at the University of Minnesota was supported by the US National Science Foundation (Grant CHE1058248 to L.Q) and the Dr. Venkateswarlu Pothapragada and Family Fellowship (to M.P.). XAS data were collected at beamline 9-3 of the Stanford Synchrotron Radiation Lightsource supported by the US-NIH and US-DOE. We thank Catexel for a generous gift of tritosyl-1,4,7-triazacyclononane
Format: application/pdf
Citation: 020944
ISSN: 0002-7863 (versió paper)
1520-5126 (versió electrònica)
Document access: http://hdl.handle.net/10256/10333
Language: eng
Publisher: American Chemical Society (ACS)
Collection: MINECO/PN 2013-2015/CTQ2012-37420-C02-01
MICINN/PN 2010-2016/CSD2010-00065
AGAUR/2009-2014/2009 SGR-637
Reproducció digital del document publicat a: http://dx.doi.org/10.1021/ja412059c
Articles publicats (D-Q)
info:eu-repo/grantAgreement/EC/FP7/303522
info:eu-repo/grantAgreement/EC/FP7/268445
info:eu-repo/grantAgreement/EC/FP7/239910
Is part of: © Journal of the American Chemical Society, 2014, vol. 136, p. 4624-4633
Rights: Tots els drets reservats
Subject: Fotocatàlisi
Photocatalysis
Sofre -- Compostos
Sulphur compounds
Reaccions químiques
Chemical reactions
Title: Triggering the generation of an iron(IV)-oxo compound and its reactivity toward sulfides by RuII photocatalysis
Type: info:eu-repo/semantics/article
Repository: DUGiDocs

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