1
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Kakiuchi Y, Docherty SR, Berkson ZJ, Yakimov AV, Wörle M, Copéret C, Aghazada S. Origin of Reactivity Trends of an Elusive Metathesis Intermediate from NMR Chemical Shift Analysis of Surrogate Analogues. J Am Chem Soc 2024; 146:20168-20182. [PMID: 38980045 DOI: 10.1021/jacs.4c05193] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/10/2024]
Abstract
Olefin metathesis has become an efficient tool in synthetic organic chemistry to build carbon-carbon bonds, thanks to the development of Grubbs- and Schrock-type catalysts. Olefin coordination, a key and often rate-determining elementary step for d0 Schrock-type catalysts, has been rarely explored due to the lack of accessible relevant molecular analogues. Herein, we present a fully characterized surrogate of this key olefin-coordination intermediate, namely, a cationic d0 tungsten oxo-methylidene complex bearing two N-heterocyclic carbene ligands─[WO(CH2)Cl(IMes)2](OTf) (1) (IMes = 1,3-dimesitylimidazole-2-ylidene, OTf-triflate counteranion), resulting in a trigonal bipyramidal (TBP) geometry, along with its neutral octahedral analogue [WO(CH2)Cl2(IMes)2] (2)─and an isostructural oxo-methylidyne derivative [WO(CH)Cl(IMes)2] (3). The analysis of their solid-state 13C and 183W MAS NMR signatures, along with computed 17O NMR parameters, helps to correlate their electronic structures with NMR patterns and evidences the importance of the competition among the three equatorial ligands in the TBP complexes. Anchored on experimentally obtained NMR parameters for 1, computational analysis of a series of olefin coordination intermediates highlights the interplay between σ- and π-donating ligands in modulating their stability and further paralleling their reactivity. NMR spectroscopy descriptors reveal the origin for the advantage of the dissymmetry in σ-donating abilities of ancillary ligands in Schrock-type catalysts: weak σ-donors avoid the orbital-competition with the oxo ligand upon formation of a TBP olefin-coordination intermediate, while stronger σ-donors compromise M≡O triple bonding and thus render olefin coordination step energy demanding.
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Affiliation(s)
- Yuya Kakiuchi
- Department of Chemistry and Applied Biosciences, ETH Zürich, Zürich CH-8093, Switzerland
| | - Scott R Docherty
- Department of Chemistry and Applied Biosciences, ETH Zürich, Zürich CH-8093, Switzerland
| | - Zachariah J Berkson
- Department of Chemistry and Applied Biosciences, ETH Zürich, Zürich CH-8093, Switzerland
| | - Alexander V Yakimov
- Department of Chemistry and Applied Biosciences, ETH Zürich, Zürich CH-8093, Switzerland
| | - Michael Wörle
- Department of Chemistry and Applied Biosciences, ETH Zürich, Zürich CH-8093, Switzerland
| | - Christophe Copéret
- Department of Chemistry and Applied Biosciences, ETH Zürich, Zürich CH-8093, Switzerland
| | - Sadig Aghazada
- Department of Chemistry and Applied Biosciences, ETH Zürich, Zürich CH-8093, Switzerland
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2
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Berkson ZJ, Bernhardt M, Copéret C. Solid-State 183W NMR Spectroscopy as a High-Resolution Probe of Polyoxotungstate Structures and Dynamics. J Phys Chem Lett 2024; 15:1950-1955. [PMID: 38346175 DOI: 10.1021/acs.jpclett.4c00033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/23/2024]
Abstract
Polyoxometalates such as ammonium paratungstate (APT) constitute an important class of metal oxides with applications for catalysis, (opto)electronics, and functional materials. Structural analyses of solid polyoxometalates mostly rely on X-ray or neutron diffraction techniques, which are largely limited to compounds that can be isolated with long-range crystallographic order. While 183W NMR has been shown to probe polyoxotungstate structures and dynamics in solution, its application to solids has been extremely limited. Here, state-of-the-art methods for the detection of solid-state 183W NMR spectra are tested and compared for APT in different hydration states. The highly resolved solid-state spectra distinguish each crystallographically distinct site in the tungstate structure. Furthermore, the 183W chemical shifts are shown to be highly sensitive to the local structure, dynamics, and symmetry of APT, establishing solid-state 183W NMR spectroscopy as a potent probe for analysis of polyoxotungstates and other tungsten-derived materials to complement solution NMR and diffraction-based techniques.
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Affiliation(s)
- Zachariah J Berkson
- Department of Chemistry and Applied Biosciences, ETH Zürich, Zürich CH-8093, Switzerland
| | - Moritz Bernhardt
- Department of Chemistry and Applied Biosciences, ETH Zürich, Zürich CH-8093, Switzerland
| | - Christophe Copéret
- Department of Chemistry and Applied Biosciences, ETH Zürich, Zürich CH-8093, Switzerland
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3
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Garcia de Castro R, Bertrand J, Rigaud B, Devers E, Digne M, Lamic-Humblot AF, Pirngruber G, Carrier X. Surface-Dependent Activation of Model α-Al 2 O 3 -Supported P-Doped Hydrotreating Catalysts Prepared by Spin Coating. Chemistry 2020; 26:14623-14638. [PMID: 32579726 DOI: 10.1002/chem.202001882] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Indexed: 11/08/2022]
Abstract
Requirements for improved catalytic formulations is continuously driving research in hydrotreating (HDT) catalysis for biomass upgrading and heteroatom removal for cleaner fuels. The present work proposes a surface-science approach for the understanding of the genesis of the active (sulfide) phase in model P-doped MoS2 hydrotreating catalysts supported on α-Al2 O3 single crystals. This approach allows one to obtain a surface-dependent insight by varying the crystal orientations of the support. Model phosphorus-doped catalysts are prepared via spin-coating of Mo-P precursor solutions onto four α-Al2 O3 crystal orientations, C(0001), A(11 2 ‾ 0), M(10 1 ‾ 0) and R(1 1 ‾ 02) that exhibit different speciations of surface -OH. 31 P and 95 Mo liquid-state NMR are used to give a comprehensive description of the Mo and P speciation of the phospho-molybdic precursor solution. The speciation of the deposition solution is then correlated with the genesis of the active MoS2 phase. XPS quantification of the surface P/Mo ratio reveal a surface-dependent phosphate aggregation driven by the amount of free phosphates in solution. Phosphates aggregation decreases in the following order C(0001)≫M(10 1 ‾ 0)>A(11 2 ‾ 0), R(1 1 ‾ 02). This evolution can be rationalized by an increasing strength of phosphate/surface interactions on the different α-Al2 O3 surface orientations from the C(0001) to the R(1 1 ‾ 02) plane. Retardation of the sulfidation with temperature is observed for model catalysts with the highest phosphate dispersion on the surface (A(11 2 ‾ 0), R(1 1 ‾ 02)), suggesting that phosphorus strongly intervene in the genesis of the active phase through a close intimacy between phosphates and molybdates. The surface P/Mo ratio appears as a key descriptor to quantify this retarding effect. It is proposed that retardation of sulfidation is driven by two effects: i) a chemical inhibition through formation of hardly reducible mixed molybdo-phosphate structures and ii) a physical inhibition with phosphate clusters inhibiting the growth of MoS2 . The surface-dependent phosphorus doping on model α-Al2 O3 supports can be used as a guide for the rational design of more efficient HDT catalysts on industrial γ-Al2 O3 carrier.
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Affiliation(s)
- Ricardo Garcia de Castro
- Sorbonne Université, CNRS, Laboratoire de Réactivité de Surface, UMR CNRS 7197, 75005, Paris, France.,Direction of Catalysis, Biocatalysis and Separation, IFP Energies Nouvelles, Rond-point de l'échangeur de Solaize, 69360, Solaize, France
| | - Jérémy Bertrand
- Sorbonne Université, CNRS, Laboratoire de Réactivité de Surface, UMR CNRS 7197, 75005, Paris, France
| | - Baptiste Rigaud
- Sorbonne Université, CNRS, Institut des Matériaux de Paris-Centre, FR CNRS 2482 7197, 75005, Paris, France
| | - Elodie Devers
- Direction of Catalysis, Biocatalysis and Separation, IFP Energies Nouvelles, Rond-point de l'échangeur de Solaize, 69360, Solaize, France
| | - Mathieu Digne
- Direction of Catalysis, Biocatalysis and Separation, IFP Energies Nouvelles, Rond-point de l'échangeur de Solaize, 69360, Solaize, France
| | | | - Gerhard Pirngruber
- Direction of Catalysis, Biocatalysis and Separation, IFP Energies Nouvelles, Rond-point de l'échangeur de Solaize, 69360, Solaize, France
| | - Xavier Carrier
- Sorbonne Université, CNRS, Laboratoire de Réactivité de Surface, UMR CNRS 7197, 75005, Paris, France
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4
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Haouas M, Trébosc J, Roch-Marchal C, Cadot E, Taulelle F, Martineau-Corcos C. High-field 95 Mo and 183 W static and MAS NMR study of polyoxometalates. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2017; 55:902-908. [PMID: 28437584 DOI: 10.1002/mrc.4601] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2017] [Revised: 04/18/2017] [Accepted: 04/19/2017] [Indexed: 06/07/2023]
Abstract
The potential of high-field NMR to measure solid-state 95 Mo and 183 W NMR in polyoxometalates (POMs) is explored using some archetypical structures like Lindqvist, Keggin and Dawson as model compounds that are well characterized in solution. NMR spectra in static and under magic angle spinning (MAS) were obtained, and their analysis allowed extraction of the NMR parameters, including chemical shift anisotropy and quadrupolar coupling parameters. Despite the inherent difficulties of measurement in solid state of these low-gamma NMR nuclei, due mainly to the low spectral resolution and poor signal-to-noise ratio, the observed global trends compare well with the solution-state NMR data. This would open an avenue for application of solid-state NMR to POMs, especially when liquid-state NMR is not possible, e.g., for poorly soluble or unstable compounds in solution, and for giant molecules with slow tumbling motion. This is the case of Keplerate where we provide here the first NMR characterization of this class of POMs in the solid state. Copyright © 2017 John Wiley & Sons, Ltd.
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Affiliation(s)
- Mohamed Haouas
- ILV, UMR CNRS 8180, UVSQ, Versailles, 78035, Cedex, France
| | - Julien Trébosc
- Univ. de Lille Nord de France, Lille, 59000, France
- CNRS UMR 8181, UCCS; USTL, Villeneuve d'Ascq, 59652, France
| | | | - Emmanuel Cadot
- ILV, UMR CNRS 8180, UVSQ, Versailles, 78035, Cedex, France
| | | | - Charlotte Martineau-Corcos
- ILV, UMR CNRS 8180, UVSQ, Versailles, 78035, Cedex, France
- CEMHTI, CNRS UPR 3079, Orléans Cedex 2, 45071, France
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5
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Uehara K, Miyachi T, Nakajima T, Mizuno N. Effects of Heteroatoms on Electronic States of Divanadium-Substituted γ-Keggin-type Polyoxometalates. Inorg Chem 2014; 53:3907-18. [DOI: 10.1021/ic5005209] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Kazuhiro Uehara
- Department of Applied Chemistry, School
of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - Takuya Miyachi
- Department of Applied Chemistry, School
of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - Takahito Nakajima
- RIKEN Advanced Institute for Computational Science, Computational Molecular Science
Research Team, 7-1-26,
Minatojima-minami-machi, Chuo-ku, Kobe, Hyogo, 650-0047, Japan
| | - Noritaka Mizuno
- Department of Applied Chemistry, School
of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
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6
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Iijima T, Yamase T, Tansho M, Shimizu T, Nishimura K. Electron Localization of Polyoxomolybdates with ε-Keggin Structure Studied by Solid-State 95Mo NMR and DFT Calculation. J Phys Chem A 2014; 118:2431-41. [DOI: 10.1021/jp409969g] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Affiliation(s)
- Takahiro Iijima
- Institute for Molecular Science, Okazaki, 444-8585, Japan
- The Graduate University for Advanced Studies (SOKENDAI), Okazaki, 444-8585, Japan
| | - Toshihiro Yamase
- Tokyo Institute of Technology, Nagatsuta,
Yokohama 226-8503, Japan
- MO Device Corporation, Kanazawa 920-0335, Japan
| | - Masataka Tansho
- National Institute for Materials Science, Tsukuba 305-0003, Japan
| | - Tadashi Shimizu
- National Institute for Materials Science, Tsukuba 305-0003, Japan
| | - Katsuyuki Nishimura
- Institute for Molecular Science, Okazaki, 444-8585, Japan
- The Graduate University for Advanced Studies (SOKENDAI), Okazaki, 444-8585, Japan
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7
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Izarova NV, Vankova N, Banerjee A, Jameson GB, Heine T, Schinle F, Hampe O, Kortz U. A noble-metalate bowl: the polyoxo-6-vanado(V)-7-palladate(II) [Pd7V6O24(OH)2]6-. Angew Chem Int Ed Engl 2011; 49:7807-11. [PMID: 20839194 DOI: 10.1002/anie.201001738] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Natalya V Izarova
- Jacobs University, School of Engineering and Science, Postfach 750561, 28725 Bremen, Germany
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8
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McGregor D, Burton-Pye BP, Howell RC, Mbomekalle IM, Lukens WW, Bian F, Mausolf E, Poineau F, Czerwinski KR, Francesconi LC. Synthesis, Structure Elucidation, and Redox Properties of 99Tc Complexes of Lacunary Wells−Dawson Polyoxometalates: Insights into Molecular 99Tc−Metal Oxide Interactions. Inorg Chem 2011; 50:1670-81. [DOI: 10.1021/ic102111t] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Donna McGregor
- Hunter College of the City University of New York, 695 Park Avenue, New York, New York 10065, United States
- Graduate Center of the City University of New York, New York, New York 10016, United States
| | - Benjamin P. Burton-Pye
- Hunter College of the City University of New York, 695 Park Avenue, New York, New York 10065, United States
| | - Robertha C. Howell
- Hunter College of the City University of New York, 695 Park Avenue, New York, New York 10065, United States
| | - Israel M. Mbomekalle
- Hunter College of the City University of New York, 695 Park Avenue, New York, New York 10065, United States
| | - Wayne W. Lukens
- Chemical Sciences Division, The Glenn T. Seaborg Center, E.O. Lawrence Berkeley National Laboratory (LBNL), One Cyclotron Road, Berkeley, California 94720, United States
| | - Fang Bian
- Hunter College of the City University of New York, 695 Park Avenue, New York, New York 10065, United States
- Graduate Center of the City University of New York, New York, New York 10016, United States
| | - Edward Mausolf
- Department of Chemistry, University of Nevada Las Vegas, Las Vegas, Nevada 89154, United States
| | - Frederic Poineau
- Department of Chemistry, University of Nevada Las Vegas, Las Vegas, Nevada 89154, United States
| | - Kenneth R. Czerwinski
- Department of Chemistry, University of Nevada Las Vegas, Las Vegas, Nevada 89154, United States
| | - Lynn C. Francesconi
- Hunter College of the City University of New York, 695 Park Avenue, New York, New York 10065, United States
- Graduate Center of the City University of New York, New York, New York 10016, United States
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9
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Cuny J, Sykina K, Fontaine B, Le Pollès L, Pickard CJ, Gautier R. 95Mo nuclear magnetic resonance parameters of molybdenum hexacarbonyl from density functional theory: appraisal of computational and geometrical parameters. Phys Chem Chem Phys 2011; 13:19471-9. [DOI: 10.1039/c1cp22289a] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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10
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Izarova NV, Vankova N, Banerjee A, Jameson GB, Heine T, Schinle F, Hampe O, Kortz U. Edelmetallatschale: Das Polyoxo-6-vanado(V)-7-palladat(II) [Pd7V6O24(OH)2]6−. Angew Chem Int Ed Engl 2010. [DOI: 10.1002/ange.201001738] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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11
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Lee U, Joo HC, Park KM, Mal S, Kortz U, Keita B, Nadjo L. Einbau von Platin(IV) in Polyoxometallate: Synthese von [H2PtIVV9O28]5− und Charakterisierung durch195Pt-NMR- Spektroskopie. Angew Chem Int Ed Engl 2008. [DOI: 10.1002/ange.200703082] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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12
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Lee U, Joo HC, Park KM, Mal SS, Kortz U, Keita B, Nadjo L. Facile Incorporation of Platinum(IV) into Polyoxometalate Frameworks: Preparation of [H2PtIVV9O28]5− and Characterization by195Pt NMR Spectroscopy. Angew Chem Int Ed Engl 2008; 47:793-6. [PMID: 18098259 DOI: 10.1002/anie.200703082] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Uk Lee
- Department of Chemistry, Pukyong National University, 599-1 Daeyeon-3dong, Nam-ku, Busan 608-737, South Korea.
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13
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Leclerc-Laronze N, Marrot J, Hervé G, Thouvenot R, Cadot E. The Heteropolytungstate Core {BW13O46}11− Derived as Monomer, Dimer, and Trimer. Chemistry 2007; 13:7234-45. [PMID: 17579901 DOI: 10.1002/chem.200601873] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
A study of the borotungstate system has led to the characterization of new, original compounds based on the unconventional Keggin derivative [H(3)BW(13)O(46)](8-) ion (denoted as 1). [H(3)BW(14)O(48)](6-) (2) and the dimer [H(6)B(2)W(26)O(90)](12-) (3) crystallize as mixed cesium/ammonium salts and have been characterized by single-crystal X-ray diffraction analysis. Anion 2 reveals an unusual arrangement, consisting of an outer {W(3)O(9)} core grafted onto the monovacant [BW(11)O(39)](9-) Keggin moiety and exhibits an unprecedented distorted square-pyramidal arrangement for a cis-{WO(2)} core. Elemental analysis, supported by bond distance analysis, is consistent with the presence of three protons distributed over the terminal oxygens of the outer {W(3)O(7)} capping fragment. The [H(6)B(2)W(26)O(90)](12-) ion (3) is formally derived from the direct condensation of two [H(3)BW(13)O(46)](8-) subunits. The cisoid arrangement of the two [BW(11)O(39)](9-) subunits, coupled with the antiparallel arrangement of the two quasi-linear O=W...O=W-OH2 chains within the central {W(4)O(12)} connecting group, breaks any symmetry, thereby resulting in a chiral compound. Polarography and pH-metric titrations reveal the formation of the monomeric precursor [H(3)BW(13)O(46)](8-) (anion 1) under stoichiometric conditions. (183)W NMR analysis of 2 and 3 in solution gives complex spectra, consistent with the presence of equilibria between several species. In the frame of this study, we also report on a structural re-investigation of the [H(6)B(3)W(39)O(132)](15-) ion (4) based on reliable results obtained in the solid state by means of single-crystal X-ray diffraction analysis, and in solution by means of 1D and 2D COSY (183)W NMR. X-ray diffraction analysis revealed the presence of three attached aquo ligands on the central {W(6)O(15)} connecting core, generating three O=W...O=W-OH2 quasi-linear chains, which are responsible for the chirality of the trimeric assembly. This structural arrangement accounts for the 39-line (183)W solution spectrum. The 2D COSY spectrum permits reliable assignments of the six strongly shielded resonances (around -250 and -400 ppm) to the six central W atoms, as well as additional assignments. The origin of such strong shielding for these particular W atoms is discussed on the basis of previously published results. Infrared data for compounds 1, 3, and 4 are also presented.
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Affiliation(s)
- Nathalie Leclerc-Laronze
- Université de Versailles Saint Quentin, Institut Lavoisier de Versailles, ILV, UMR CNRS 8180, 45 Avenue des Etats-Unis, 78035 Versailles Cedex, France
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14
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Structure of double Keggin-Ti/W-mixed polyanion [(A-β-GeTi3W9O37)2O3]14− and multielectron-transfer-based photocatalyic H2-generation. ACTA ACUST UNITED AC 2007. [DOI: 10.1016/j.molcata.2006.08.040] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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15
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Abstract
This paper deals with the catalytic properties of different supported heteropolyacids (HPAs), both molybdenum- and tungsten-based, in the oxidative desulfurization process of diesel. We are jointly developing a new oxidative desulfurization process, aimed at reducing the sulfur content in diesel to less than 10 ppm (parts per million) using in situ produced peroxides. In this new process, high-molecular-weight organosulfur compounds, such as 4,6-dimethyl-dibenzothiophene (DMDBT), difficult to be eliminated by conventional hydrodesulfurization, are oxidized to the corresponding sulfones and subsequently removed by adsorption. Molybdenum-based HPAs, with Keggin structure, proved to be the most active and selective catalysts for oxidizing DMDBT with on-stream lifetimes exceeding 1500 h time on stream (t.o.s.).
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16
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Gracia J, Poblet JM, Fernández JA, Autschbach J, Kazansky LP. DFT Calculations of the
183
W NMR Chemical Shifts in Reduced Polyoxotungstates. Eur J Inorg Chem 2006. [DOI: 10.1002/ejic.200500833] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Jose Gracia
- Departament de Quimica Fisica i Inorgánica, Universitat Rovira i Virgili, Marcel.lí Domingo s/n, Campus Sescelades, 43007 Tarragona, Spain
| | - Josep M. Poblet
- Departament de Quimica Fisica i Inorgánica, Universitat Rovira i Virgili, Marcel.lí Domingo s/n, Campus Sescelades, 43007 Tarragona, Spain
| | - Jorge A. Fernández
- Departament de Quimica Fisica i Inorgánica, Universitat Rovira i Virgili, Marcel.lí Domingo s/n, Campus Sescelades, 43007 Tarragona, Spain
| | - Jochen Autschbach
- Department of Chemistry, State University of New York at Buffalo, 312 Natural Sciences Complex, Buffalo, NY 14260‐3000, USA
| | - Leonid P. Kazansky
- Institute of Physical chemistry, Russian Academy of Sciences, 31, Leninski pr, Moscow 119991, Russia
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17
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Gracia J, Poblet JM, Autschbach J, Kazansky LP. Density-Functional Calculation of the183W and17O NMR Chemical Shifts for Large Polyoxotungstates. Eur J Inorg Chem 2006. [DOI: 10.1002/ejic.200500832] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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18
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d'Espinose de Lacaillerie JB, Barberon F, Romanenko KV, Lapina OB, Pollès LL, Gautier R, Gan Z. 95Mo Magic Angle Spinning NMR at High Field: Improved Measurements and Structural Analysis of the Quadrupole Interaction in Monomolybdates and Isopolymolybdates. J Phys Chem B 2005; 109:14033-42. [PMID: 16852762 DOI: 10.1021/jp0519621] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In this study, 95Mo quadrupole couplings in various molydbates were measured easily and accurately with magic angle spinning (MAS) NMR under a directing field of 19.6 T. The resonance frequency of 54 MHz was sufficiently high to remove acoustic ringing artifacts, and the spectra could be analyzed in the usual terms of chemical shift and quadrupolar line shapes. For monomolybdates and molybdite, the quadrupole coupling dominated the NMR response, and the quadrupole parameters could be measured with better accuracy than in previous lower field studies. Moreover, despite the low symmetry of the molybdenum coordination, the usefulness of such measurements to probe molybdenum environments was established by ab initio density functional theory (DFT) calculations of the electric field gradient from known structures. The experimental NMR data correlated perfectly with the refined structures. In isopolymolybdates, the resonances were shapeless and DFT calculations were impossible because of the large and low symmetry unit cells. Nevertheless, empirical but clear NMR signatures were obtained from the spinning sidebands analysis or the MQMAS spectra. This was possible for the first time thanks to the improved baseline and sensitivity at high fields. With the generalization of NMR spectrometers operating above 17 T, it was predicted that 95Mo MAS NMR could evolve as a routine characterization tool for ill-defined structures such as supported molybdates in catalysis.
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Affiliation(s)
- Jean-Baptiste d'Espinose de Lacaillerie
- Laboratoire de Physique Quantique, UMR CNRS SIEN 7142, Ecole Supérieure de Physique et de Chimie Industrielles, 10 rue Vauquelin, 75231 Paris Cedex 05, France.
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