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Highly Effective Water Oxidation Catalysis with Iridium Complexes through the Use of NaIO4

Exceptional water oxidation (WO) turnover frequencies (TOF=17 000 h-1), and turnover numbers (TONs) close to 400 000, the largest ever reported for a metal-catalyzed WO reaction, have been found by using [Cp*IrIII (NHC)Cl2] (in which NHC=3-methyl-1-(1 phenylethyl)-im-Idazoline-2-ylidene) as the pre-catalyst and NaIO4 as oxidant in water at 40ºC. The apparent TOF for [Cp*IrIII (NHC)X2] (1X, in which X stands for I (1I), Cl (1Cl), or triflate anion (1OTf)) and [(Cp*-NHCMe)IrIIII2] (2) complexes, is kept constant during almost all of the O2 evolution reaction when using NaIO4 as oxidant. The TOF was found to be dependent on the ligand and on the anion (TOF ranging from ≈ 600 to ≈1100 h-1 at 25ºC). Degradation of the complexes by oxidation of the organic ligands upon reaction with NaIO4 has been investigated. ¹H NMR, ESI-MS, and dynamic light-scattering measurements (DLS) of the reaction medium indicated that the complex undergoes ràpid degradation, even at low equivalents of oxidant, but this process takes place without formation of nanoparticles. Remarkably, three-month-old solution samples of oxidized pre-catalysts remain equally as active as freshly prepared solutions. A UV/Vis feature band at ƴmax=405 nm is observed in catalytic reaction solutions only when O2 evolves, which may be attributed to a resting state iridium speciation, most probably Ir–oxo species with an oxidation state higher than IV

Wiley-VCH Verlag Berlin

Director: Ministerio de Ciencia e Innovación (Espanya)
Autor: Codolà Duch, Zoel
Cardoso, Joao M. S.
Royo, Beatriz
Costas Salgueiro, Miquel
Lloret Fillol, Julio
Data: 2013
Resum: Exceptional water oxidation (WO) turnover frequencies (TOF=17 000 h-1), and turnover numbers (TONs) close to 400 000, the largest ever reported for a metal-catalyzed WO reaction, have been found by using [Cp*IrIII (NHC)Cl2] (in which NHC=3-methyl-1-(1 phenylethyl)-im-Idazoline-2-ylidene) as the pre-catalyst and NaIO4 as oxidant in water at 40ºC. The apparent TOF for [Cp*IrIII (NHC)X2] (1X, in which X stands for I (1I), Cl (1Cl), or triflate anion (1OTf)) and [(Cp*-NHCMe)IrIIII2] (2) complexes, is kept constant during almost all of the O2 evolution reaction when using NaIO4 as oxidant. The TOF was found to be dependent on the ligand and on the anion (TOF ranging from ≈ 600 to ≈1100 h-1 at 25ºC). Degradation of the complexes by oxidation of the organic ligands upon reaction with NaIO4 has been investigated. ¹H NMR, ESI-MS, and dynamic light-scattering measurements (DLS) of the reaction medium indicated that the complex undergoes ràpid degradation, even at low equivalents of oxidant, but this process takes place without formation of nanoparticles. Remarkably, three-month-old solution samples of oxidized pre-catalysts remain equally as active as freshly prepared solutions. A UV/Vis feature band at ƴmax=405 nm is observed in catalytic reaction solutions only when O2 evolves, which may be attributed to a resting state iridium speciation, most probably Ir–oxo species with an oxidation state higher than IV
Format: application/pdf
Accés al document: http://hdl.handle.net/10256/8640
Llenguatge: eng
Editor: Wiley-VCH Verlag Berlin
Col·lecció: info:eu-repo/semantics/altIdentifier/doi/10.1002/chem.201204568
info:eu-repo/semantics/altIdentifier/issn/0947-6539
info:eu-repo/semantics/altIdentifier/eissn/1521-3765
MICINN/PN 2010-2012/CTQ2009-08464
info:eu-repo/grantAgreement/EC/FP7/239910/EU/Bio-inspired Design of Catalysts for Selective Oxidations of C-H and C=C Bonds/BIDECASEOX
info:eu-repo/grantAgreement/EC/FP7/268445/EU/Modular Ligands for Water Splitting/WATERSPLIT
Drets: Tots els drets reservats
Matèria: Catàlisi homogènia
Homogeneous catalysis
Catalitzadors d’iridi
Iridium catalysts
Espectroscòpia ultraviolada-visible
Ultraviolet-visible spectroscopy
Títol: Highly Effective Water Oxidation Catalysis with Iridium Complexes through the Use of NaIO4
Tipus: info:eu-repo/semantics/article
Repositori: DUGiDocs

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