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Zakary O, Body M, Charpentier T, Sarou-Kanian V, Legein C. Structural Modeling of O/F Correlated Disorder in TaOF 3 and NbOF 3-x(OH) x by Coupling Solid-State NMR and DFT Calculations. Inorg Chem 2023; 62:16627-16640. [PMID: 37747836 DOI: 10.1021/acs.inorgchem.3c02844] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/27/2023]
Abstract
The structure of MOF3 (M = Nb, Ta) compounds was precisely modeled by combining powder X-ray diffraction, solid-state NMR spectroscopy, and semiempirical dispersion-corrected DFT calculations. It consists of stacked ∞(MOF3) layers along the c⃗ direction formed by heteroleptic corner-connected MX6 (X = O, F) octahedra. 19F NMR resonance assignments and occupancy rates of the anionic crystallographic sites have been revised. The bridging site is shared equally by the anions, and the terminal site is occupied by F only. An O/F correlated disorder is expected since cis-MO2F4 octahedra are favored, resulting in one-dimensional -F-M-O-M- strings along the <100> and <010> directions. Ten different 2 × 2 × 1 supercells per compound, fulfilling these characteristics, were built. Using DFT calculations and the GIPAW approach, the supercells were relaxed and the 19F isotropic chemical shift values were determined. The agreement between the experimental and calculated 19F spectra is excellent for TaOF3. The 1H and 19F experimental NMR spectra revealed that some of the bridging F atoms are substituted by OH groups, especially in NbOF3. New supercells involving OH groups were generated. Remarkably, the best agreement is obtained for the supercells with the composition closest to that estimated from the 19F NMR spectra, i.e., NbOF2.85(OH)0.15.
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Affiliation(s)
- Ouail Zakary
- Institut des Molécules et Matériaux du Mans (IMMM) - UMR 6283 CNRSLe Mans Université, 72805 Le Mans Cedex 9, France
| | - Monique Body
- Institut des Molécules et Matériaux du Mans (IMMM) - UMR 6283 CNRSLe Mans Université, 72805 Le Mans Cedex 9, France
| | | | | | - Christophe Legein
- Institut des Molécules et Matériaux du Mans (IMMM) - UMR 6283 CNRSLe Mans Université, 72805 Le Mans Cedex 9, France
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2
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Lange MA, Khan I, Dören R, Ashraf M, Qurashi A, Prädel L, Panthöfer M, von der Au M, Cossmer A, Pfeifer J, Meermann B, Mondeshki M, Tahir MN, Tremel W. High-speed solid state fluorination of Nb 2O 5 yields NbO 2F and Nb 3O 7F with photocatalytic activity for oxygen evolution from water. Dalton Trans 2021; 50:6528-6538. [PMID: 34002749 DOI: 10.1039/d1dt00533b] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Solid state reactions are slow because the diffusion of atoms or ions through the reactant, intermediate and crystalline product phases is the rate-limiting step. This requires days or even weeks of high temperature treatment, and consumption of large amounts of energy. We employed spark-plasma sintering, an engineering technique that is used for high-speed consolidation of powders with a pulsed electric current passing through the sample to carry out the fluorination of niobium oxide in minute intervals. The approach saves time and large amounts of waste energy. Moreover, it allows the preparation of fluorinated niobium oxides on a gram scale using poly(tetrafluoroethylene) (®Teflon) scrap and without toxic chemicals. The synthesis can be upscaled easily to the kg range with appropriate sintering equipment. Finally, NbO2F and Nb3O7F prepared by spark plasma sintering show significant photoelectrocatalytic (PEC) oxygen evolution from water in terms of photocurrent density and incident photon-to-current efficiency (% IPCE), whereas NbO2F and Nb3O7F prepared by conventional high temperature chemistry show little to no PEC response. Our study is a proof of concept for the quick, clean and energy saving production of valuable photocatalysts from plastic waste.
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Affiliation(s)
- Martin Alexander Lange
- Department Chemie, Johannes Gutenberg-Universität Mainz, Duesbergweg 10-14, D-55128 Mainz, Germany.
| | - Ibrahim Khan
- Center of Excellence in Nanotechnology, King Fahd University of Petroleum & Minerals, Dhahran, 31262, Saudi Arabia
| | - René Dören
- Department Chemie, Johannes Gutenberg-Universität Mainz, Duesbergweg 10-14, D-55128 Mainz, Germany.
| | - Muhammad Ashraf
- Chemistry Department, King Fahd University of Petroleum & Materials, Dharan 31261, P.O. Box 5048, Kingdom of Saudi Arabia.
| | - Ahsanulhaq Qurashi
- Center of Excellence in Nanotechnology, King Fahd University of Petroleum & Minerals, Dhahran, 31262, Saudi Arabia
| | - Leon Prädel
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Martin Panthöfer
- Department Chemie, Johannes Gutenberg-Universität Mainz, Duesbergweg 10-14, D-55128 Mainz, Germany.
| | - Marcus von der Au
- Bundesanstalt für Materialforschung und -prüfung (BAM), Anorganische Spurenanalytik, Richard-Willstätter-Straße 11, D-12489 Berlin, Germany
| | - Antje Cossmer
- Bundesanstalt für Materialforschung und -prüfung (BAM), Anorganische Spurenanalytik, Richard-Willstätter-Straße 11, D-12489 Berlin, Germany
| | - Jens Pfeifer
- Bundesanstalt für Materialforschung und -prüfung (BAM), Anorganische Spurenanalytik, Richard-Willstätter-Straße 11, D-12489 Berlin, Germany
| | - Björn Meermann
- Bundesanstalt für Materialforschung und -prüfung (BAM), Anorganische Spurenanalytik, Richard-Willstätter-Straße 11, D-12489 Berlin, Germany
| | - Mihail Mondeshki
- Department Chemie, Johannes Gutenberg-Universität Mainz, Duesbergweg 10-14, D-55128 Mainz, Germany.
| | - Muhammad Nawaz Tahir
- Chemistry Department, King Fahd University of Petroleum & Materials, Dharan 31261, P.O. Box 5048, Kingdom of Saudi Arabia.
| | - Wolfgang Tremel
- Department Chemie, Johannes Gutenberg-Universität Mainz, Duesbergweg 10-14, D-55128 Mainz, Germany.
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3
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Coordination complexes and applications of transition metal sulfide and selenide halides. Coord Chem Rev 2020. [DOI: 10.1016/j.ccr.2020.213512] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
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4
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Bartalucci N, Marchetti F, Zacchini S, Pampaloni G. Decarbonylation of phenylacetic acids by high valent transition metal halides. Dalton Trans 2019; 48:5725-5734. [DOI: 10.1039/c9dt00551j] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The unusual decarbonylation of α-phenyl carboxylic acids with suitable substituents is a general reaction promoted at room temperature by homoleptic halides of high valent transition metals.
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Affiliation(s)
- Niccolò Bartalucci
- Dipartimento di Chimica e Chimica Industriale
- Università di Pisa
- I-56124 Pisa
- Italy
| | - Fabio Marchetti
- Dipartimento di Chimica e Chimica Industriale
- Università di Pisa
- I-56124 Pisa
- Italy
| | - Stefano Zacchini
- Dipartimento di Chimica Industriale “Toso Montanari”
- Università di Bologna
- I-40136 Bologna
- Italy
| | - Guido Pampaloni
- Dipartimento di Chimica e Chimica Industriale
- Università di Pisa
- I-56124 Pisa
- Italy
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Hirai D, Sawai O, Nunoura T, Hiroi Z. Facile synthetic route to transition metal oxyfluorides via reactions between metal oxides and PTFE. J Fluor Chem 2018. [DOI: 10.1016/j.jfluchem.2018.02.008] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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Dabachi J, Body M, Galven C, Boucher F, Legein C. Preparation-Dependent Composition and O/F Ordering in NbO 2F and TaO 2F. Inorg Chem 2017; 56:5219-5232. [PMID: 28398062 DOI: 10.1021/acs.inorgchem.7b00355] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Through an analysis combining powder XRD, TGA, and 19F and 1H solid-state NMR, it is confirmed for NbO2F and shown for TaO2F that both contain hydroxyl defects and metal vacancies when prepared by aqueous solution synthesis. The formulations M1-x□xO2-5x(OH,F)1+5x of both the samples are determined. The effects of the usually applied thermal treatments are examined. Obtaining pure NbO2F and TaO2F from these samples, that is, fully removing metal vacancies and hydroxide, while avoiding the formation of M2O5, is not that easy. Since thermal treatments result in dehydroxylation and defluorination, it requires, at least, a larger amount of fluorine than metal initially, which may not be the case. We also confirm that the solid-state synthesis is an efficient method to avoid metal vacancies and hydroxyl defects in NbO2F and then apply it to the synthesis of TaO2F. The local structure of NbO2F and TaO2F is poorly described by an ideal cubic ReO3-type model with O and F randomly distributed over the available anion sites. Since O/F ordering was previously highlighted, NbO2F and TaO2F cubic 3 × 3 × 3 supercells featuring -M-O-M-O-M-F- chains along ⟨100⟩ have been built and geometry optimized. These optimized supercells lead to more realistic structures than the previously proposed models, that is, really disordered structures with angularly and radially distorted MX6 octahedra as expected in disordered compounds. Moreover, the structural modeling of NbO2F and TaO2F by these geometry-optimized supercells is supported by the computed 19F and 93Nb NMR parameters, which give very good agreement with the experimental ones.
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Affiliation(s)
- Jamal Dabachi
- Université Bretagne Loire, Université du Maine , UMR CNRS 6283, Institut des Molécules et des Matériaux du Mans (IMMM), Avenue Olivier Messiaen, 72085 Le Mans Cedex 9, France
| | - Monique Body
- Université Bretagne Loire, Université du Maine , UMR CNRS 6283, Institut des Molécules et des Matériaux du Mans (IMMM), Avenue Olivier Messiaen, 72085 Le Mans Cedex 9, France
| | - Cyrille Galven
- Université Bretagne Loire, Université du Maine , UMR CNRS 6283, Institut des Molécules et des Matériaux du Mans (IMMM), Avenue Olivier Messiaen, 72085 Le Mans Cedex 9, France
| | - Florent Boucher
- Institut des Matériaux Jean Rouxel (IMN), Université de Nantes, CNRS , 2 Rue de la Houssinière, BP 32229, 44322 Nantes Cedex 3, France
| | - Christophe Legein
- Université Bretagne Loire, Université du Maine , UMR CNRS 6283, Institut des Molécules et des Matériaux du Mans (IMMM), Avenue Olivier Messiaen, 72085 Le Mans Cedex 9, France
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Bortoluzzi M, Ferretti E, Marchetti F, Pampaloni G, Pinzino C, Zacchini S. Coordination Compounds of Niobium(IV) Oxide Dihalides Including the Synthesis and the Crystallographic Characterization of NHC Complexes. Inorg Chem 2016; 55:4173-82. [PMID: 27082642 DOI: 10.1021/acs.inorgchem.5b02888] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The 1:1 molar reactions of NbOX3 with SnBu3H, in toluene at 0 °C in the presence of oxygen/nitrogen donors, resulted in the formation of NbOX2L2 (X = Cl, L2 = dme, 2a; X = Br, L2 = dme, 2b; X = Cl, L = thf, 2c; X = Cl, L = NCMe, 2d; dme = 1,2-dimethoxyethane, thf = tetrahydrofuran), in good yields. The 1:2 reactions of freshly prepared 2d and 2b with the bulky NHC ligands 1,3-bis(2,4,6-trimethylphenyl)imidazol-2-ylidene, Imes, and 1,3-bis(2,6-dimethylphenyl)imidazol-2-ylidene, Ixyl, respectively, afforded the complexes NbOCl2(Imes)2, 3, and NbOBr2(Ixyl)2, 4, in 50-60% yields. The reactions of 2b with NaOR, in tetrahydrofuran, gave NbOCl(OR) (R = Ph, 5; R = Me, 6) in about 60% yields. All the products were characterized by analytical and spectroscopic techniques; moreover DFT calculations were carried out in order to shed light on synthetic and structural features. Compounds 3 and 4, whose molecular structures have been ascertained by X-ray diffraction, represent very rare examples of crystallographically characterized niobium-NHC systems.
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Affiliation(s)
- Marco Bortoluzzi
- Dipartimento di Scienze Molecolari e Nanosistemi, Università di Venezia Ca' Foscari , Via Torino 155, I-30170 Mestre, Venice, Italy
| | - Eleonora Ferretti
- Dipartimento di Chimica e Chimica Industriale, Università di Pisa , Via G. Moruzzi 13, I-56124 Pisa, Italy
| | - Fabio Marchetti
- Dipartimento di Chimica e Chimica Industriale, Università di Pisa , Via G. Moruzzi 13, I-56124 Pisa, Italy
| | - Guido Pampaloni
- Dipartimento di Chimica e Chimica Industriale, Università di Pisa , Via G. Moruzzi 13, I-56124 Pisa, Italy
| | - Calogero Pinzino
- ICCOM-CNR UOS Pisa , Research Area, Via Moruzzi 1, I-56124 Pisa, Italy
| | - Stefano Zacchini
- Dipartimento di Chimica Industriale "Toso Montanari", Università di Bologna , Viale Risorgimento 4, I-40136 Bologna, Italy
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9
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Nakhal S, Lerch M. New transition metal oxide fluorides with ReO3-type structure. ZEITSCHRIFT FUR NATURFORSCHUNG SECTION B-A JOURNAL OF CHEMICAL SCIENCES 2016. [DOI: 10.1515/znb-2015-0215] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Abstract
The new niobium oxide fluorides MNbO2F4 [M = (Cr, Fe)], CrNb2O4F5, and Fe2Nb3O6F9 were prepared by treatment of chromium or iron nitrate with Nb-containing hydrofluoric acid solutions. Crystal structures were investigated by means of X-ray powder diffraction. All new compounds can be structurally refined in the cubic ReO3-type. The iron niobium oxide fluorides are reddish orange, and chromium containing phases exhibit a light green color. The niobium atoms are in the highest formal oxidation state.
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Affiliation(s)
- Suliman Nakhal
- Institut für Chemie , Technische Universität Berlin , D-10623 Berlin, Germany
| | - Martin Lerch
- Institut für Chemie , Technische Universität Berlin , D-10623 Berlin, Germany
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10
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Dabachi J, Body M, Dittmer J, Fayon F, Legein C. Structural refinement of the RT LaOF phases by coupling powder X-Ray diffraction, (19)F and (139)La solid state NMR and DFT calculations of the NMR parameters. Dalton Trans 2015; 44:20675-84. [PMID: 26565802 DOI: 10.1039/c5dt04028k] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The structures of the β- and t-LaOF phases have been refined from XRPD patterns. For both phases, (19)F and (139)La solid-state NMR spectra recorded at high magnetic fields show the presence of a single F and a single La local environment, indicating a full anionic ordering in these oxyfluoride compounds. DFT calculations of the (19)F and (139)La chemical shielding tensors and of the (139)La EFG tensor have been performed for the proposed structural models. The observed good agreement between experimental and calculated NMR parameters for both phases highlights the accuracy of the structural data.
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Affiliation(s)
- Jamal Dabachi
- LUNAM Université, Université du Maine, CNRS UMR 6283, Institut des Molécules et des Matériaux du Mans (IMMM), Avenue Olivier Messiaen, F-72085 Le Mans Cedex 9, France.
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11
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Nakhal S, Bredow T, Lerch M. Syntheses and Crystal Structures of New ReO3-Type-Derived Transition Metal Oxide Fluorides. Z Anorg Allg Chem 2015. [DOI: 10.1002/zaac.201500089] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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12
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Levason W, Reid G, Zhang W. Six-coordinate NbF5 and TaF5 complexes with tertiary mono-phosphine and -arsine ligands. J Fluor Chem 2015. [DOI: 10.1016/j.jfluchem.2015.01.010] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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13
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Leblanc M, Maisonneuve V, Tressaud A. Crystal Chemistry and Selected Physical Properties of Inorganic Fluorides and Oxide-Fluorides. Chem Rev 2014; 115:1191-254. [DOI: 10.1021/cr500173c] [Citation(s) in RCA: 110] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Marc Leblanc
- LUNAM
Université, CNRS UMR 6283, Institut des Molécules et
des Matériaux du Mans, Faculté des Sciences et Techniques, Université du Maine, 72085 Le Mans Cedex 9, France
| | - Vincent Maisonneuve
- LUNAM
Université, CNRS UMR 6283, Institut des Molécules et
des Matériaux du Mans, Faculté des Sciences et Techniques, Université du Maine, 72085 Le Mans Cedex 9, France
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14
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Levason W, Reid G, Trayer J, Zhang W. Synthesis, properties and structures of NbOF3 complexes and comparisons with NbOCl3 analogues. Dalton Trans 2014; 43:3649-59. [DOI: 10.1039/c3dt53322k] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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15
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Lu H, Gautier R, Donakowski MD, Liu Z, Poeppelmeier KR. From Solution to the Solid State: Control of Niobium Oxide–Fluoride [NbOxFy]n− Species. Inorg Chem 2013; 53:537-42. [DOI: 10.1021/ic402561g] [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]
Affiliation(s)
- Hongcheng Lu
- State Key Laboratory of Solidification
Processing, School of Materials Science and Engineering, Northwestern Polytechnical University, 127 Youyixilu Road, Xi’an 710072, China
- Department of Chemistry, Northwestern University, 2145 Sheridan
Road, Evanston, Illinois 60208, United States
| | - Romain Gautier
- Department of Chemistry, Northwestern University, 2145 Sheridan
Road, Evanston, Illinois 60208, United States
| | - Martin D. Donakowski
- Department of Chemistry, Northwestern University, 2145 Sheridan
Road, Evanston, Illinois 60208, United States
| | - Zhengtang Liu
- State Key Laboratory of Solidification
Processing, School of Materials Science and Engineering, Northwestern Polytechnical University, 127 Youyixilu Road, Xi’an 710072, China
| | - Kenneth R. Poeppelmeier
- Department of Chemistry, Northwestern University, 2145 Sheridan
Road, Evanston, Illinois 60208, United States
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Biswal M, Body M, Legein C, Sadoc A, Boucher F. NbF5 and TaF5: Assignment of 19F NMR resonances and chemical bond analysis from GIPAW calculations. J SOLID STATE CHEM 2013. [DOI: 10.1016/j.jssc.2013.09.001] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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17
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Bortoluzzi M, Ghini F, Hayatifar M, Marchetti F, Pampaloni G, Zacchini S. Oxido- and Sulfidoniobium(V)N,N-Diethylcarbamates: Synthesis, Characterization and DFT Study. Eur J Inorg Chem 2013. [DOI: 10.1002/ejic.201300219] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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18
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Funaioli T, Marchetti F, Pampaloni G, Zacchini S. Ligand-interchange reactions between M(iv) (M = Ti, V) oxide bis-acetylacetonates and halides of high-valent group 4 and 5 metals. A synthetic and electrochemical study. Dalton Trans 2013; 42:14168-77. [DOI: 10.1039/c3dt51378e] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
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Shorafa H, Ficicioglu H, Tamadon F, Girgsdies F, Seppelt K. Molybdenum Difluoride Dioxide, MoO2F2. Inorg Chem 2010; 49:4263-7. [DOI: 10.1021/ic1000864] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Hashem Shorafa
- Anorganische und Analytische Chemie, Institut für Chemie, Freie Universität, Fabeckstrasse 34-36, D-14195 Berlin, Germany
| | - Halil Ficicioglu
- Anorganische und Analytische Chemie, Institut für Chemie, Freie Universität, Fabeckstrasse 34-36, D-14195 Berlin, Germany
| | - Farhad Tamadon
- Anorganische und Analytische Chemie, Institut für Chemie, Freie Universität, Fabeckstrasse 34-36, D-14195 Berlin, Germany
| | - Frank Girgsdies
- Department of Inorganic Chemistry, Fritz Haber Institut, Faradayweg 4-6, D-14195 Berlin, Germany
| | - Konrad Seppelt
- Anorganische und Analytische Chemie, Institut für Chemie, Freie Universität, Fabeckstrasse 34-36, D-14195 Berlin, Germany
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20
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Le Berre F, Crosnier-Lopez MP, Galven C, Fourquet JL, Legein C, Body M, Buzaré JY. Ca2+/vacancies and O2−/F−ordering in new oxyfluoride pyrochlores Li2xCa1.5−x□0.5−xM2O6F (M = Nb,Ta) for 0 ≤ x ≤ 0.5. Dalton Trans 2007:2457-66. [PMID: 17844668 DOI: 10.1039/b701863k] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
New oxyfluorides Li(2x)Ca(1.5-x) square (0.5-x)M2O6F (M = Nb, Ta), belonging to the cubic pyrochlore structural type (Z = 8, a approximately 10.5 angstroms), were synthesized by solid state reaction for 0 < or = x < or = 0.5. XRD data allowed us to determine their structures from single crystals for the two alpha and beta-Ca(1.5) square (0.5)Nb2O6F forms and from powder samples for the others. This characterisation was completed by TEM and solid state 19F NMR experiments. For the Ca(1.5) square (0.5)M2O6F (x = 0) pyrochlore phases, the presence of a double ordering phenomenon is demonstrated, involving on one hand the Ca(2+) ions and the vacancies and on the other hand the oxide and the fluoride anions which are strictly located in the 8b sites of the Fd3m aristotype space group. The Ca(2+) ions/vacancies ordering leads to a reversible phase transition, a (P4(3)32) <--> beta (Fd3m). The 19F NMR study strongly suggests that, in the beta-phases, the fluoride ions are only on average at the centre of the Ca3 square tetrahedron. It shows that slightly different Ca-F distances occuring in alpha-Ca(1.5) square (0.5)Nb2O6F may be related to a more difficult thermal ionic and vacancies diffusion process than in the tantalate compound. This may explain the hysteresis phenomenon presented by the phase transition. A solid solution Li(2x)Ca(1.5-x) square (0.5-x) Ta2O6F (0 < or = x < or = 0.5) was prepared and the order-disorder phase transition observed for Ca(1.5) square (0.5)M2MO6F compounds disappears for all the other compositions where less or no more vacancies exist in the 16d sites. In the LiCaM2O6F compounds, the 19F NMR study allows us to determine the Ca(2+) and Li+ ions distributions around the fluoride ions and shows that the [FLi2Ca2] environment is clearly favoured.
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Abstract
Pauling's second crystal rule is shown to be able to predict in a general and simple way the distribution of anions in mixed oxyanion systems such as oxynitrides and oxyhalides with diverse compositions and structure types. Results are presented in a plot correlating the charge of the anions obtained from the observed occupancies in crystallographic positions with the calculated bond strength sums for these sites.
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Affiliation(s)
- Amparo Fuertes
- Institut de Ciència de Materials de Barcelona (C.S.I.C.), Campus U.A.B., 08193 Bellaterra, Spain.
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22
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An electron diffraction and bond valence sum investigation of oxygen/fluorine ordering in NbnO2n−1Fn+2,. J SOLID STATE CHEM 2006. [DOI: 10.1016/j.jssc.2005.10.014] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Supeł J, Marx R, Seppelt K. Preparation and Structure of Rhenium Fluoride Trioxide ReO3F, and the Polymorphism of Rhenium Trifluoride Dioxide, ReO2F3. Z Anorg Allg Chem 2005. [DOI: 10.1002/zaac.200500239] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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24
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Cordier S, Roisnel T, Poulain M. Synthesis and characterization of the novel Nb3O5F5 niobium oxyfluoride: the term n=3 of the NbnO2n−1Fn+2 series. J SOLID STATE CHEM 2004. [DOI: 10.1016/j.jssc.2004.05.032] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Cordier S, Hernandez O, Thépot JY, Shames AI, Perrin C. Synthesis, crystal structure, and characterization of the first Nb(3) triangular cluster compound bonded to fluorine ligands: association of Nb(3)I(i)F(i)(3)F(a)(8)L(a) units and Nb(IV)L(6) Octahedra with L=O and F. Inorg Chem 2003; 42:1101-6. [PMID: 12588144 DOI: 10.1021/ic025667w] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The synthesis and the crystal structure of the first compound containing Nb(3) triangular clusters bonded to fluorine ligands are presented in this work. The structure of Nb(3)IF(7)L(NbL(2))(0.25) with L = O and F, determined by single-crystal X-ray diffraction, is based on a Nb(3)I(i)F(i)(3)F(a)(8)L(a) unit and a NbL(6) octahedron (tetragonal, space group I4/m, a = 13.8638(3) A, c = 8.9183(2) A, V = 1714.14(7) A(3), Z = 8). Two crystallographic positions (noted L5 and L6) are randomly occupied by fluorine and oxygen with two different F:O occupancies. These L ligands build an octahedral site for a single niobium atom, located between the units. The four L5 ligands of the NbL(6) octahedron are shared with four Nb(3) cluster units, while the two other L6 ligands are terminal. The Nb(3) cluster is face-capped by one iodine and edge-bridged by three fluorine ligands. Two of the three niobium atoms constituting the cluster are bonded to three additional apical fluorine ligands, while the third one is bonded to two fluorines and one L5 ligand. The Nb(3) cluster is linked to six adjacent ones via all the apical fluorine ligands. The developed formula of the unit is therefore Nb(3)I(i)F(i)(3)F(a)(-)(a)(8/2)L(a) according to the Schäfer and Schnering notation. The oxidation state of the single niobium and the random distribution of fluorine and oxygen on the two L sites will be discussed on the basis of structural analysis, the bond valence method, and IR and EPR measurements. The structural results will be compared to those of previously reported niobium compounds containing NbF(6) or Nb(F,O)(6) octahedra.
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Affiliation(s)
- S Cordier
- Laboratoire de Chimie du Solide et Inorganique Moléculaire (LCSIM), Institut de Chimie de Rennes, UMR 6511 CNRS-Université de Rennes 1, France
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