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Activation of H2O2 over Zr(IV). Insights from Model Studies on Zr-Monosubstituted Lindqvist Tungstates

  • Dades identificatives

    Identificador: imarina:9226648
    Autors:
    Maksimchuk, Nataliya V.Evtushok, Vasilii Yu.Zalomaeva, Olga V.Maksimov, Gennadii M.Ivanchikova, Irina D.Chesalov, Yuriy A.Eltsov, Ilia V.Abramov, Pavel A.Glazneva, Tatyana S.Yanshole, Vadim V.Kholdeeva, Oxana A.Errington, R. JohnSole-Daura, AlbertPoblet, Josep M.Carbo, Jorge J.
    Resum:
    Zr-monosubstituted Lindqvist- type polyoxometalates (Zr-POMs), (Bu4N)(2)[W5O18Zr(H2O)(3)] (1) and (Bu4N)(6)[{W5O18Zr(mu-OH)}(2)] (2), have been employed as molecular models to unravel the mechanism of hydrogen peroxide activation over Zr(IV) sites. Compounds 1 and 2 are hydrolytically stable and catalyze the epoxidation of C.C bonds in unfunctionalized alkenes and alpha,beta-unsaturated ketones, as well as sulfoxidation of thioethers. Monomer 1 is more active than dimer 2. Acid additives greatly accelerate the oxygenation reactions and increase oxidant utilization efficiency up to >99%. Product distributions are indicative of a heterolytic oxygen transfer mechanism that involves electrophilic oxidizing species formed upon the interaction of Zr-POM and H2O2. The interaction of 1 and 2 with H2O2 and the resulting peroxo derivatives have been investigated by UV-vis, FTIR, Raman spectroscopy, HR-ESI-MS, and combined HPLC-ICP-atomic emission spectroscopy techniques. The interaction between an O-17-enriched dimer, (Bu4N)(6)[{W5O18Zr(mu-OCH3)}2] (2'), and H2O2 was also analyzed by O-17 NMR spectroscopy. Combining these experimental studies with DFT calculations suggested the existence of dimeric peroxo species [(mu-eta(2):eta(2)-O-2){ZrW5O18}(2)](6-) as well as monomeric Zr-hydroperoxo [W5O18Zr(eta(2)-OOH)](3-) and Zr-peroxo [HW5O18Zr(eta(2)-O-2)](3-) species. Reactivity studies revealed that the dimeric peroxo is inert toward alkenes but is able to transfer oxygen atoms to thioethers, while the monomeric peroxo intermediate is capable of epoxidizing C.C bonds. DFT analysis of the reaction mechanism identifies the monomeric Zr-hydroperoxo intermediate as the real epoxidizing species and the corresponding alpha-oxygen transfer to the substrate as the rate-determining step. The
  • Altres:

    Autor segons l'article: Maksimchuk, Nataliya V.; Evtushok, Vasilii Yu.; Zalomaeva, Olga V.; Maksimov, Gennadii M.; Ivanchikova, Irina D.; Chesalov, Yuriy A.; Eltsov, Ilia V.; Abramov, Pavel A.; Glazneva, Tatyana S.; Yanshole, Vadim V.; Kholdeeva, Oxana A.; Errington, R. John; Sole-Daura, Albert; Poblet, Josep M.; Carbo, Jorge J.;
    Departament: Química Física i Inorgànica
    Autor/s de la URV: Carbó Martin, Jorge Juan / Poblet Rius, Josep Maria / Solé Daura, Albert
    Paraules clau: Zirconium compounds Zirconium Utilization efficiency Unsaturated ketones Unsaturated compounds Unfunctionalized alkenes Tungsten compounds Titanium compounds Thioether oxidation Thianthrene 5-oxide Substrates Silanol-functionalized polyoxotungstates Selective epoxidation Reactivity studies Reaction intermediates Rate determining step Product distributions Polyoxometalates Oxygen Oxidation Olefins Nuclear magnetic resonance spectroscopy Niobium compounds Metal-organic framework Mesoporous niobium-silicates Mechanistic probe Lindqvist tungstate Ketones Hydrogen-peroxide Hydrogen peroxide activation Hydrogen peroxide Free energy Fourier transform infrared spectroscopy Epoxidation Dimers Dft Coordination environment Chemical activation Catalytic-properties Catalysts Atomic emission spectroscopy Alkene epoxidation Additives
    Resum: Zr-monosubstituted Lindqvist- type polyoxometalates (Zr-POMs), (Bu4N)(2)[W5O18Zr(H2O)(3)] (1) and (Bu4N)(6)[{W5O18Zr(mu-OH)}(2)] (2), have been employed as molecular models to unravel the mechanism of hydrogen peroxide activation over Zr(IV) sites. Compounds 1 and 2 are hydrolytically stable and catalyze the epoxidation of C.C bonds in unfunctionalized alkenes and alpha,beta-unsaturated ketones, as well as sulfoxidation of thioethers. Monomer 1 is more active than dimer 2. Acid additives greatly accelerate the oxygenation reactions and increase oxidant utilization efficiency up to >99%. Product distributions are indicative of a heterolytic oxygen transfer mechanism that involves electrophilic oxidizing species formed upon the interaction of Zr-POM and H2O2. The interaction of 1 and 2 with H2O2 and the resulting peroxo derivatives have been investigated by UV-vis, FTIR, Raman spectroscopy, HR-ESI-MS, and combined HPLC-ICP-atomic emission spectroscopy techniques. The interaction between an O-17-enriched dimer, (Bu4N)(6)[{W5O18Zr(mu-OCH3)}2] (2'), and H2O2 was also analyzed by O-17 NMR spectroscopy. Combining these experimental studies with DFT calculations suggested the existence of dimeric peroxo species [(mu-eta(2):eta(2)-O-2){ZrW5O18}(2)](6-) as well as monomeric Zr-hydroperoxo [W5O18Zr(eta(2)-OOH)](3-) and Zr-peroxo [HW5O18Zr(eta(2)-O-2)](3-) species. Reactivity studies revealed that the dimeric peroxo is inert toward alkenes but is able to transfer oxygen atoms to thioethers, while the monomeric peroxo intermediate is capable of epoxidizing C.C bonds. DFT analysis of the reaction mechanism identifies the monomeric Zr-hydroperoxo intermediate as the real epoxidizing species and the corresponding alpha-oxygen transfer to the substrate as the rate-determining step. The calculations also showed that protonation of Zr-POM significantly reduces the free-energy barrier of the key oxygen-transfer step because of the greater electrophilicity of the catalyst and that dimeric species hampers the approach of alkene substrates due to steric repulsions reducing its reactivity. The improved performance of the Zr(IV) catalyst relative to Ti(IV) and Nb(V) catalysts is respectively due to a flexible coordination environment and a low tendency to form energy deep-well and low-reactive Zr-peroxo intermediates.
    Àrees temàtiques: Química Materiais Interdisciplinar General chemistry Engenharias ii Ciências agrárias i Chemistry, physical Chemistry (miscellaneous) Chemistry (all) Catalysis Astronomia / física
    Accès a la llicència d'ús: https://creativecommons.org/licenses/by/3.0/es/
    Adreça de correu electrònic de l'autor: josepmaria.poblet@urv.cat j.carbo@urv.cat
    Identificador de l'autor: 0000-0002-4533-0623 0000-0002-3945-6721
    Data d'alta del registre: 2024-07-27
    Versió de l'article dipositat: info:eu-repo/semantics/acceptedVersion
    Enllaç font original: https://pubs.acs.org/doi/full/10.1021/acscatal.1c02485
    URL Document de llicència: https://repositori.urv.cat/ca/proteccio-de-dades/
    Referència a l'article segons font original: Acs Catalysis. 11 (16): 10589-10603
    Referència de l'ítem segons les normes APA: Maksimchuk, Nataliya V.; Evtushok, Vasilii Yu.; Zalomaeva, Olga V.; Maksimov, Gennadii M.; Ivanchikova, Irina D.; Chesalov, Yuriy A.; Eltsov, Ilia V.; (2021). Activation of H2O2 over Zr(IV). Insights from Model Studies on Zr-Monosubstituted Lindqvist Tungstates. Acs Catalysis, 11(16), 10589-10603. DOI: 10.1021/acscatal.1c02485
    DOI de l'article: 10.1021/acscatal.1c02485
    Entitat: Universitat Rovira i Virgili
    Any de publicació de la revista: 2021
    Tipus de publicació: Journal Publications
  • Paraules clau:

    Catalysis,Chemistry (Miscellaneous),Chemistry, Physical
    Zirconium compounds
    Zirconium
    Utilization efficiency
    Unsaturated ketones
    Unsaturated compounds
    Unfunctionalized alkenes
    Tungsten compounds
    Titanium compounds
    Thioether oxidation
    Thianthrene 5-oxide
    Substrates
    Silanol-functionalized polyoxotungstates
    Selective epoxidation
    Reactivity studies
    Reaction intermediates
    Rate determining step
    Product distributions
    Polyoxometalates
    Oxygen
    Oxidation
    Olefins
    Nuclear magnetic resonance spectroscopy
    Niobium compounds
    Metal-organic framework
    Mesoporous niobium-silicates
    Mechanistic probe
    Lindqvist tungstate
    Ketones
    Hydrogen-peroxide
    Hydrogen peroxide activation
    Hydrogen peroxide
    Free energy
    Fourier transform infrared spectroscopy
    Epoxidation
    Dimers
    Dft
    Coordination environment
    Chemical activation
    Catalytic-properties
    Catalysts
    Atomic emission spectroscopy
    Alkene epoxidation
    Additives
    Química
    Materiais
    Interdisciplinar
    General chemistry
    Engenharias ii
    Ciências agrárias i
    Chemistry, physical
    Chemistry (miscellaneous)
    Chemistry (all)
    Catalysis
    Astronomia / física
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