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G Jafari M, Fehn D, Reinholdt A, Hernández-Prieto C, Patel P, Gau MR, Carroll PJ, Krzystek J, Liu C, Ozarowski A, Telser J, Delferro M, Meyer K, Mindiola DJ. Tale of Three Molecular Nitrides: Mononuclear Vanadium (V) and (IV) Nitrides As Well As a Mixed-Valence Trivanadium Nitride Having a V 3N 4 Double-Diamond Core. J Am Chem Soc 2022; 144:10201-10219. [PMID: 35652694 DOI: 10.1021/jacs.2c00276] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Transmetallation of [VCl3(THF)3] and [TlTptBu,Me] afforded [(TptBu,Me)VCl2] (1, TptBu,Me = hydro-tris(3-tert-butyl-5-methylpyrazol-1-yl)borate), which was reduced with KC8 to form a C3v symmetric VII complex, [(TptBu,Me)VCl] (2). Complex 1 has a high-spin (S = 1) ground state and displays rhombic high-frequency and -field electron paramagnetic resonance (HFEPR) spectra, while complex 2 has an S = 3/2 4A2 ground state observable by conventional EPR spectroscopy. Complex 1 reacts with NaN3 to form the VV nitride-azide complex [(TptBu,Me)V≡N(N3)] (3). A likely VIII azide intermediate en route to 3, [(TptBu,Me)VCl(N3)] (4), was isolated by reacting 1 with N3SiMe3. Complex 4 is thermally stable but reacts with NaN3 to form 3, implying a bis-azide intermediate, [(TptBu,Me)V(N3)2] (A), leading to 3. Reduction of 3 with KC8 furnishes a trinuclear and mixed-valent nitride, [{(TptBu,Me)V}2(μ4-VN4)] (5), conforming to a Robin-Day class I description. Complex 5 features a central vanadium ion supported only by bridging nitride ligands. Contrary to 1, complex 2 reacts with NaN3 to produce an azide-bridged dimer, [{(TptBu,Me)V}2(1,3-μ2-N3)2] (6), with two antiferromagnetically coupled high-spin VII ions. Complex 5 could be independently produced along with [(κ2-TptBu,Me)2V] upon photolysis of 6 in arene solvents. The putative {VIV≡N} intermediate, [(TptBu,Me)V≡N] (B), was intercepted by photolyzing 6 in a coordinating solvent, such as tetrahydrofuran (THF), yielding [(TptBu,Me)V≡N(THF)] (B-THF). In arene solvents, B-THF expels THF to afford 5 and [(κ2-TptBu,Me)2V]. A more stable adduct (B-OPPh3) was prepared by reacting B-THF with OPPh3. These adducts of B are the first neutral and mononuclear VIV nitride complexes to be isolated.
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Affiliation(s)
- Mehrafshan G Jafari
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Dominik Fehn
- Inorganic Chemistry, Department of Chemistry and Pharmacy, Friedrich-Alexander-University Erlangen-Nürnberg (FAU), 91058 Erlangen, Germany
| | - Anders Reinholdt
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Cristina Hernández-Prieto
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Prajay Patel
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Michael R Gau
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Patrick J Carroll
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - J Krzystek
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, United States
| | - Cong Liu
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Andrew Ozarowski
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, United States
| | - Joshua Telser
- Department of Biological, Physical and Health Sciences, Roosevelt University, Chicago, Illinois 60605, United States
| | - Massimiliano Delferro
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Karsten Meyer
- Inorganic Chemistry, Department of Chemistry and Pharmacy, Friedrich-Alexander-University Erlangen-Nürnberg (FAU), 91058 Erlangen, Germany
| | - Daniel J Mindiola
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
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Cai X, Ma Y, Chu W, Yang W. Selective Oxidation of Isobutane to Methacrylic Acid by Metal-Substituted Ammonium Salts of Molybdovanadophosphoric Acid. Catal Letters 2021. [DOI: 10.1007/s10562-021-03821-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Wesinger S, Mendt M, Albert J. Alcohol‐Activated Vanadium‐Containing Polyoxometalate Complexes in Homogeneous Glucose Oxidation Identified with
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V‐NMR and EPR Spectroscopy. ChemCatChem 2021. [DOI: 10.1002/cctc.202100632] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Stefanie Wesinger
- Lehrstuhl für Chemische Reaktionstechnik Friedrich-Alexander-Universität Erlangen-Nürnberg Egerlandstr. 3 91058 Erlangen Germany
| | - Matthias Mendt
- Felix-Bloch-Institut für Festkörperphysik Universität Leipzig Linnéstraße 5 04103 Leipzig Germany
| | - Jakob Albert
- Institut für Technische und Makromolekulare Chemie Universität Hamburg Bundesstr. 45 20146 Hamburg Germany
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Chiesa M, Giamello E. On the Role and Applications of Electron Magnetic Resonance Techniques in Surface Chemistry and Heterogeneous Catalysis. Catal Letters 2021. [DOI: 10.1007/s10562-021-03576-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Abstract
Some relevant aspects of Electron Paramagnetic Resonance (EPR) applied to the fields of surface chemistry and heterogeneous catalysis are illustrated in this perspective paper that aims to show the potential of these techniques in describing critical features of surface structures and reactivity. Selected examples are employed covering distinct aspects of catalytic science from morphological analysis of surfaces to detailed descriptions of chemical bonding and catalytic sites topology. In conclusions the pros and cons related to the acquisition of EPR instrumentations in an advanced laboratory of surface chemistry and heterogeneous catalysis are briefly considered.
Graphic Abstract
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5
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Electron paramagnetic resonance study of vanadium exchanged H-ZSM5 prepared by vapor reaction of VCl4. The role of 17O isotope labelling in the characterisation of the metal oxide interaction. J Catal 2020. [DOI: 10.1016/j.jcat.2020.06.029] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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6
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Babazadeh M, Hosseinzadeh-Khanmiri R, Zakhireh S. Eco-friendly synthesis of benzoxazepine and malonamide derivatives in aqueous media. Appl Organomet Chem 2016. [DOI: 10.1002/aoc.3463] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Mirzaagha Babazadeh
- Department of Chemistry, Tabriz Branch; Islamic Azad University; Tabriz Iran
| | | | - Solmaz Zakhireh
- Department of Chemistry, Tabriz Branch; Islamic Azad University; Tabriz Iran
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8
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Morra E, Maurelli S, Chiesa M, Giamello E. Rational Design of Engineered Multifunctional Heterogeneous Catalysts. The Role of Advanced EPR Techniques. Top Catal 2015. [DOI: 10.1007/s11244-015-0418-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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9
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Li Y, Li B, Geng L, Wang J, Wang Y, Huang J. The Hydroxylation of Aromatics with Oxygen by Vanadium Catalysts Supported on N-doped Carbon Materials. Catal Letters 2015. [DOI: 10.1007/s10562-015-1478-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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10
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Peys N, Maurelli S, Reekmans G, Adriaensens P, De Gendt S, Hardy A, Van Doorslaer S, Van Bael MK. Chemical composition of an aqueous oxalato-/citrato-VO(2+) solution as determinant for vanadium oxide phase formation. Inorg Chem 2014; 54:69-78. [PMID: 25517211 DOI: 10.1021/ic5015779] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Aqueous solutions of oxalato- and citrato-VO(2+) complexes are prepared, and their ligand exchange reaction is investigated as a function of the amount of citrate present in the aqueous solution via continuous-wave electron paramagnetic resonance (CW EPR) and hyperfine sublevel correlation (HYSCORE) spectroscopy. With a low amount of citrate, monomeric cis-oxalato-VO(2+) complexes occur with a distorted square-pyramidal geometry. As the amount of citrate increases, oxalate is gradually exchanged for citrate. This leads to (i) an intermediate situation of monomeric VO(2+) complexes with a mix of oxalate/citrate ligands and (ii) a final situation of both monomeric and dimeric complexes with exclusively citrato ligands. The monomeric citrato-VO(2+) complexes dominate (abundance > 80%) and are characterized by a 6-fold chelation of the vanadium(IV) ion by 4 RCO2(-) ligands at the equatorial positions and a H2O/R-OH ligand at the axial position. The different redox stabilities of these complexes, relative to that of dissolved O2 in the aqueous solution, is analyzed via (51)V NMR. It is shown that the oxidation rate is the highest for the oxalato-VO(2+) complexes. In addition, the stability of the VO(2+) complexes can be drastically improved by evacuation of the dissolved O2 from the solution and subsequent storage in a N2 ambient atmosphere. The vanadium oxide phase formation process, starting with the chemical solution deposition of the aqueous solutions and continuing with subsequent processing in an ambient 0.1% O2 atmosphere, differs for the two complexes. The oxalato-VO(2+) complexes turn into the oxygen-deficient crystalline VO2 B at 400 °C, which then turns into crystalline V6O13 at 500 °C. In contrast, the citrato-VO(2+) complexes form an amorphous film at 400 °C that crystallizes into VO2 M1 and V6O13 at 500 °C.
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Affiliation(s)
- Nick Peys
- Institute for Materials Research, Inorganic and Physical Chemistry and ‡Applied and Analytical Chemistry, Institute for Materials Research, Hasselt University , Diepenbeek, Belgium
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11
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Dai L, You W, Li Y, Liu L, Ge X, Che W. A new Keggin-templated heterometal-oxide-based organic–inorganic hybrid compound. Inorganica Chim Acta 2014. [DOI: 10.1016/j.ica.2014.01.030] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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12
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Grinenval E, Bayard F, Basset JM, Lefebvre F. Formation of a Covalent Bond between a Polyoxometalate and Silica Covered by SiH Moieties. Inorg Chem 2014; 53:2022-9. [DOI: 10.1021/ic4023163] [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)
- Eva Grinenval
- CPE Lyon, CNRS, UMR C2P2, LCOMS, Bâtiment CPE Curien, Université Lyon 1 , 43 Boulevard du 11 Novembre 1918, F-69616 Villeurbanne, France
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13
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TAYEBEE REZA, MALEKI BEHROUZ. Assembling of H5PW10V2O40/MCM-48 and studying its superior catalytic performance in the synthesis of 14-aryl-14-H-dibenzo[a, j]xanthenes. J CHEM SCI 2013. [DOI: 10.1007/s12039-013-0372-3] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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14
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Efremenko I, Neumann R. Computational insight into the initial steps of the Mars-van Krevelen mechanism: electron transfer and surface defects in the reduction of polyoxometalates. J Am Chem Soc 2012; 134:20669-80. [PMID: 23210519 DOI: 10.1021/ja308625q] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Metal oxides as a rule oxidize and oxygenate substrates via the Mars-van Krevelen mechanism. A well-defined α-Keggin polyoxometalate, H(5)PV(2)Mo(10)O(40), can be viewed as an analogue of discrete structure that reacts via the Mars-van Krevelen mechanism both in solution and in the gas phase. Guided by previous experimental observations, we have studied the key intermediates on the reaction pathways of its reduction by various compounds using high-level DFT calculations. These redox reactions of polyoxometalates require protons, and thus such complexes were explicitly considered. First, the energetics of outer-sphere proton and electron transfer as well as coupled proton and electron transfer were calculated for seven substrates. This was followed by identification of possible key intermediates on the subsequent reaction pathways that feature displacement of the metal atom from the Keggin structure and coordinatively unsaturated sites on the H(5)PV(2)Mo(10)O(40) surface. Such metal defects are favored at vanadium sites. For strong reducing agents the initial outer-sphere electron transfer, alone or possibly coupled with proton transfer, facilitates formation of metal defects. Subsequent coordination allows for formation of reactive ensembles on the catalyst surface, for which the selective oxygen-transfer step becomes feasible. Weak reducing agents do not facilitate defect formation by outer-sphere electron and/or proton transfers, and thus formation of metal defect structures prior to the substrate activation is suggested as an initial step. Calculated geometries and energies of metal defect structures support experimentally observed intermediates and demonstrate the complex nature of the Mars-van Krevelen mechanism.
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Affiliation(s)
- Irena Efremenko
- Department of Organic Chemistry, Weizmann Institute of Science, Rehovot 76100, Israel
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15
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Jakes P, Eichel RA. Characterization of tetravalent vanadium functional centres in metal oxides derived from a spin-Hamiltonian analysis. Mol Phys 2012. [DOI: 10.1080/00268976.2011.640954] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022]
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16
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Zhao P, Leng Y, Zhang M, Wang J, Wu Y, Huang J. A polyoxometalate-based PdII-coordinated ionic solid catalyst for heterogeneous aerobic oxidation of benzene to biphenyl. Chem Commun (Camb) 2012; 48:5721-3. [DOI: 10.1039/c2cc31919e] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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17
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Jakes P, Blickhan N, Jekewitz T, Drochner A, Vogel H, Fuess H, Eichel RA. Interplay between Defect Structure and Catalytic Activity in the Mo10−xVxOy Mixed-Oxide System. Chemphyschem 2011; 12:3578-83. [DOI: 10.1002/cphc.201100393] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2011] [Indexed: 11/12/2022]
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18
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Legagneux N, Jeanneau E, Thomas A, Taoufik M, Baudouin A, de Mallmann A, Basset JM, Lefebvre F. Grafting Reaction of Platinum Organometallic Complexes on Silica-Supported or Unsupported Heteropolyacids. Organometallics 2011. [DOI: 10.1021/om1003539] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Nicolas Legagneux
- Université de Lyon ICL, C2P2 UMR 5265 (CNRS−CPE−Université Lyon 1), LCOMS−CPE Lyon 43 Boulevard du 11 Novembre 1918 F-69616, Villeurbanne, France
| | - Erwann Jeanneau
- Centre de Diffractométrie Henri Longchambon (UCBL), Bâtiment Raulin, 43 Boulevard du 11 Novembre 1918, 69616 Villeurbanne Cedex, France
| | - Amélie Thomas
- Université de Lyon ICL, C2P2 UMR 5265 (CNRS−CPE−Université Lyon 1), LCOMS−CPE Lyon 43 Boulevard du 11 Novembre 1918 F-69616, Villeurbanne, France
| | - Mostafa Taoufik
- Université de Lyon ICL, C2P2 UMR 5265 (CNRS−CPE−Université Lyon 1), LCOMS−CPE Lyon 43 Boulevard du 11 Novembre 1918 F-69616, Villeurbanne, France
| | - Anne Baudouin
- Université de Lyon ICL, C2P2 UMR 5265 (CNRS−CPE−Université Lyon 1), LCOMS−CPE Lyon 43 Boulevard du 11 Novembre 1918 F-69616, Villeurbanne, France
| | - Aimery de Mallmann
- Université de Lyon ICL, C2P2 UMR 5265 (CNRS−CPE−Université Lyon 1), LCOMS−CPE Lyon 43 Boulevard du 11 Novembre 1918 F-69616, Villeurbanne, France
| | - Jean-Marie Basset
- Université de Lyon ICL, C2P2 UMR 5265 (CNRS−CPE−Université Lyon 1), LCOMS−CPE Lyon 43 Boulevard du 11 Novembre 1918 F-69616, Villeurbanne, France
| | - Frédéric Lefebvre
- Université de Lyon ICL, C2P2 UMR 5265 (CNRS−CPE−Université Lyon 1), LCOMS−CPE Lyon 43 Boulevard du 11 Novembre 1918 F-69616, Villeurbanne, France
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Kaminker I, Goldberg H, Neumann R, Goldfarb D. High-field pulsed EPR spectroscopy for the speciation of the reduced [PV(2)Mo(10)O(40)](6-) polyoxometalate catalyst used in electron-transfer oxidations. Chemistry 2011; 16:10014-20. [PMID: 20645349 DOI: 10.1002/chem.201000944] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
An in-depth spectroscopic EPR investigation of a key intermediate, formally notated as [PV(IV)V(V)Mo(10)O(40)](6-) and formed in known electron-transfer and electron-transfer/oxygen-transfer reactions catalyzed by H(5)PV(2)Mo(10)O(40), has been carried out. Pulsed EPR spectroscopy have been utilized: specifically, W-band electron-electron double resonance (ELDOR)-detected NMR and two-dimensional (2D) hyperfine sub-level correlation (HYSCORE) measurements, which resolved (95)Mo and (17)O hyperfine interactions, and electron-nuclear double resonance (ENDOR), which gave the weak (51)V and (31)P interactions. In this way, two paramagnetic species related to [PV(IV)V(V)Mo(10)O(40)](6-) were identified. The first species (30-35 %) has a vanadyl (VO(2+))-like EPR spectrum and is not situated within the polyoxometalate cluster. Here the VO(2+) was suggested to be supported on the Keggin cluster and can be represented as an ion pair, [PV(V)Mo(10)O(39)](8-)[V(IV)O(2+)]. This species originates from the parent H(5)PV(2)Mo(10)O(40) in which the vanadium atoms are nearest neighbors and it is suggested that this isomer is more likely to be reactive in electron-transfer/oxygen-transfer reaction oxidation reactions. In the second (70-65 %) species, the V(IV) remains embedded within the polyoxometalate framework and originates from reduction of distal H(5)PV(2)Mo(10)O(40) isomers to yield an intact cluster, [PV(IV)V(V)Mo(10)O(40)](6-).
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Affiliation(s)
- Ilia Kaminker
- Department of Chemical Physics, Weizmann Institute of Science, Rehovot, 76100 Israel
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Khenkin AM, Leitus G, Neumann R. Electron Transfer−Oxygen Transfer Oxygenation of Sulfides Catalyzed by the H5PV2Mo10O40 Polyoxometalate. J Am Chem Soc 2010; 132:11446-8. [DOI: 10.1021/ja105183w] [Citation(s) in RCA: 95] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Alexander M. Khenkin
- Department of Organic Chemistry and Chemical Reseach Support Unit, Weizmann Institute of Science, Rehovot, Israel 76100
| | - Gregory Leitus
- Department of Organic Chemistry and Chemical Reseach Support Unit, Weizmann Institute of Science, Rehovot, Israel 76100
| | - Ronny Neumann
- Department of Organic Chemistry and Chemical Reseach Support Unit, Weizmann Institute of Science, Rehovot, Israel 76100
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21
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A new pure Mo-oxide-based organic–inorganic hybrid framework templated by vanadium-substituted Keggin anions. INORG CHEM COMMUN 2010. [DOI: 10.1016/j.inoche.2010.01.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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22
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Dai L, You W, Wang E, Wang X, Han X, Li W, Fang Y. 2D Rhombus-grid networks constructed from vanadium-substituted Keggin-type polyoxomolybdophosphates and Cd/Zn complex fragments. Inorganica Chim Acta 2009. [DOI: 10.1016/j.ica.2009.07.031] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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23
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IR Spectroscopic Investigation of Heteropolymolybdate Catalysts: Acidic Properties and Reactivity towards Propene. Z PHYS CHEM 2009. [DOI: 10.1524/zpch.219.7.1019.67090] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Abstract
Compounds of the general type CsxH3+y−xPVyMo12−yO40 (x = 0, 2–4 with y = 1, or x = 0, 2 with y = 0) were investigated by IR spectroscopy. After thermal treatment at 473–773 K in vacuum or N2, the probe molecules CO (at 77 K, in transmission) or CO2 (at 298 K, in diffuse reflectance) were adsorbed. On the surface of Cs2H2PVMo11O40 and Cs2HPMo12O40, Brønsted acid sites were indicated by a CO band at 2162 cm−1. All Cs containing compounds produced CO bands at 2152 cm−1 or CO2 bands at 2341 cm−1. Additional weak Lewis acid sites of Mo or V in at least two oxidation states were detected after treatment at 673 K. The fraction of the reduced species decreased in the order H4PVMo11O40 > Cs2H2PVMo11O40 > Cs3HPVMo11O40. In situ DRIFT spectra of these three compounds taken during interaction with propene at up to 673 K revealed that the pattern of IR bands typical of the Keggin anion was unaffected at x = 3, altered severely for the acid and to an intermediate extent for x = 2. The changes are consistent with a diminishing of the splitting of the P–O frequency. The Keggin structure represents the initial oxidized state of the heteropoly compound catalysts. Reduction affects but does not destroy the local structure as probed by IR spectroscopy. The more easily reducible H4PVMo11O40 is active for propene oxidation at 513 K, Cs2H2PVMo11O40 only at 617 K.
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Goldberg H, Kaminker I, Goldfarb D, Neumann R. Oxidation of Carbon Monoxide Cocatalyzed by Palladium(0) and the H5PV2Mo10O40 Polyoxometalate Probed by Electron Paramagnetic Resonance and Aerobic Catalysis. Inorg Chem 2009; 48:7947-52. [DOI: 10.1021/ic900868t] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Hila Goldberg
- Department of Organic Chemistry
- Department of Chemical Physics
- Weizmann Institute of Science, Rehovot, Israel 76100
| | - Ilia Kaminker
- Department of Organic Chemistry
- Department of Chemical Physics
- Weizmann Institute of Science, Rehovot, Israel 76100
| | - Daniella Goldfarb
- Department of Organic Chemistry
- Department of Chemical Physics
- Weizmann Institute of Science, Rehovot, Israel 76100
| | - Ronny Neumann
- Department of Organic Chemistry
- Department of Chemical Physics
- Weizmann Institute of Science, Rehovot, Israel 76100
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25
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Structural evolution of H4PVMo11O40⋅xH2O during calcination and isobutane oxidation: New insights into vanadium sites by a comprehensive in situ approach. J Catal 2007. [DOI: 10.1016/j.jcat.2006.11.004] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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26
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Khenkin AM, Carl P, Baute D, Raitsimring AM, Astashkin AV, Shimon LJ, Goldfarb D, Neumann R. Structural and EPR/ENDOR/ESEEM spectroscopic investigations of a vanadomolybdate Keggin-type polyoxometalate in organic solvent. Inorganica Chim Acta 2006. [DOI: 10.1016/j.ica.2006.01.043] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Kampf M, Richter R, Griebel J, Weller A, Kirmse R. Synthese, Strukturen, EPR- und ENDOR-spektroskopische Untersuchungen an �bergangsmetallkomplexen von N, N-Diisobutyl-N?-(2, 6-difluor)benzoylselenoharnstoff. Z Anorg Allg Chem 2005. [DOI: 10.1002/zaac.200400438] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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28
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Raj NK, Ramaswamy A, Manikandan P. Oxidation of norbornene over vanadium-substituted phosphomolybdic acid catalysts and spectroscopic investigations. ACTA ACUST UNITED AC 2005. [DOI: 10.1016/j.molcata.2004.10.005] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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S. Van Doorslaer,*, Segura Y, Cool P. Structural Investigation of Vanadyl-Acetylacetonate-Containing Precursors of TiOx−VOx Mixed Oxides on SBA-15. J Phys Chem B 2004. [DOI: 10.1021/jp046611l] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- S. Van Doorslaer,*
- Laboratory for Spectroscopy in Biophysics and Catalysis, Departments of Physics, and Laboratory of Adsorption and Catalysis, Department of Chemistry, University of Antwerp, Universiteitsplein 1, B-2610 Wilrijk, Belgium
| | - Y. Segura
- Laboratory for Spectroscopy in Biophysics and Catalysis, Departments of Physics, and Laboratory of Adsorption and Catalysis, Department of Chemistry, University of Antwerp, Universiteitsplein 1, B-2610 Wilrijk, Belgium
| | - P. Cool
- Laboratory for Spectroscopy in Biophysics and Catalysis, Departments of Physics, and Laboratory of Adsorption and Catalysis, Department of Chemistry, University of Antwerp, Universiteitsplein 1, B-2610 Wilrijk, Belgium
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Kala Raj N, Deshpande S, Ingle RH, Raja T, Manikandan P. Heterogenized Molybdovanadophosphoric Acid on Amine-Functionalized SBA-15 for Selective Oxidation of Alkenes. Catal Letters 2004. [DOI: 10.1007/s10562-004-8683-0] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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31
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Gutjahr M, Hoentsch J, Böttcher R, Storcheva O, Köhler K, Pöppl A. A Q- and X-band pulsed electron nuclear double resonance study of the structure and location of the vanadyl ions in the Cs salt of heteropolyacid PVMo11O40. J Am Chem Soc 2004; 126:2905-11. [PMID: 14995208 DOI: 10.1021/ja030576z] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The location and coordination geometry of vanadium(IV) ions in the cesium salt of molybdovanadophosphoric heteropolyacid Cs(4)PVMo(11)O(40) were studied using orientation-selective pulsed ENDOR (electron nuclear double resonance) experiments. To enhance the orientation selectivity for the paramagnetic vanadyl species, these investigations were done at Q-band frequencies. It was possible to resolve interactions of the paramagnetic vanadyl ions (VO(2+)) with all relevant nuclei, (1)H, (31)P, (51)V, and (133)Cs. The location of the vanadyl species was studied by determination of the complete (31)P hyperfine tensor. This approach was done for both the fresh and the calcined Cs(4)PVMo(11)O(40) materials, and no differences in the structures of the VO(2+) complexes were found. The ENDOR results give experimental evidence for the location of the V(IV) ions. For both samples, it was possible to exclude the incorporation of V(IV) at the Mo sites. The VO(2+) species are directly attached to the outer surface of the heteropolyanion and coordinated to four of the outer oxygen atoms with a V-P distance of 3.96 A.
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Affiliation(s)
- Marlen Gutjahr
- Fakultät für Physik und Geowissenschaften, Universität Leipzig, Linnéstrasse 5, D-04103 Leipzig, Germany
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