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Kenji Nomiya - One of the best experts on this subject based on the ideXlab platform.
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Synthesis and pH-variable ultracentrifugation molecular weight measurements of the dimeric, Ti–O–Ti bridged anhydride form of a novel di-TiIV-1,2-substituted α-Keggin polyoxotungstate. Molecular structure of the [(α-1,2-PW10Ti2O39)2]10− polyoxoanion
Journal of The Chemical Society-dalton Transactions, 2020Co-Authors: Kenji Nomiya, Yoshitaka Sakai, Mizuto Takahashi, Jason A. Widegren, Takao Aizawa, Noriko Chikaraishi KasugaAbstract:The preparation and characterization of a Keggin-type, novel di-TiIV-1,2-substituted polyoxotungstate are described. The dimeric, Ti–O–Ti bridged anhydride form of the di-TiIV-1,2-substituted α-Keggin polyoxotungstate, K10[α,α-P2W20Ti4O78]·12H2O 1, was unexpectedly found in the varied molar-ratio reactions of tri-lacunary precursor Na9[A-PW9O34]·19H2O with Ti(SO4)2 in aqueous solution. Although this compound was first found as a minor product in the preparation of the dimeric, tri-TiIV-1,2,3-substituted species, K10H2[α,α-P2W18Ti6O77]·17H2O 3, it was successfully prepared as a main product in this work and structurally characterized. Compound 1, as analytically pure, homogeneous colorless needle crystals, was obtained as a major product in 29.2% yield (2.7 g scale) from recrystallization under acidic conditions (at pH 2.2) of the 1 ∶ 2 molar-ratio reaction product. X-Ray structure analysis revealed that the molecular structure of 1 consisted of a dimeric anhydride formed by two Ti–O–Ti bonds linking two [α-1,2-PW10Ti2O40]7− Keggin units. Interestingly, ultracentrifugation molecular weight (MW) measurements of this compound in aqueous solution showed the pH-dependent interconversion between monomer [α-1,2-PW10Ti2O40]7−2 and dimer [α,α-P2W20Ti4O78]10−1; this compound was present as the monomer under less acidic conditions (pH 7.8), while it was in dimeric form under more acidic conditions (pH 1.0 and 2.2). Characterization of 1 was also accomplished by complete elemental analyses, TG/DTA, FTIR and solution (31P and 183W) NMR Spectroscopy.
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A first example of polyoxotungstate-based giant molecule. Synthesis and molecular structure of a tetrapod-shaped Ti–O–Ti bridged anhydride form of Dawson tri-titanium(IV)-substituted polyoxotungstate
Dalton Transactions, 2020Co-Authors: Yoshitaka Sakai, Chika Nozaki Kato, Kenji Yoza, Kenji NomiyaAbstract:The preparation and structural characterization of a giant “tetrapod”-shaped inorganic molecule, [(α-1,2,3-P2W15Ti3O60.5)4Cl]37− ,1a (abbreviated to {TiO6}12; FW ∼15700), consisting of four tri-TiIV-1,2,3-substituted α-Dawson substructures and one encapsulated Cl− ion, are described. A water-soluble, all-inorganic composition compound of the tetrameric Ti–O–Ti bridged anhydride form, NaxH33−xK4[1a]·yH2O, 1 (x = 21–26, y = 60–70), being afforded by a stoichiometric reaction in aqueous solution of tri-lacunary Dawson polyoxotungstate Na12[B-α-P2W15O56]·19H2O with 3 equiv of Ti(SO4)2·4H2O in HCl-acidic aqueous solution followed by exchanging the countercation, was obtained as analytically pure, homogeneous colorless plate crystals. Single-crystal X-ray structure analysis revealed that the polyoxoanion 1a was an inorganic, giant “tetrapod”-shaped molecule (described as a sphere with a diameter of ∼31.2 A) with approximately Td symmetry. Characterization of 1 was also accomplished by complete elemental analysis, TG/DTA, FTIR, UV-vis absorption and solution (31P and 183W) NMR Spectroscopy.
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Monomer and Dimer of Mono-titanium(IV)-Containing α-Keggin Polyoxometalates: Synthesis, Molecular Structures, and pH-Dependent Monomer—Dimer Interconversion in Solution.
ChemInform, 2013Co-Authors: Yusuke Matsuki, Yuki Mouri, Yoshitaka Sakai, Satoshi Matsunaga, Kenji NomiyaAbstract:Compounds (III) and (IV) are characterized by single crystal XRD, FTIR, CPMAS 31P NMR, and solution 31P and 183W NMR Spectroscopy.
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Monomer and Dimer of Mono‐titanium(IV)‐Containing α‐Keggin Polyoxometalates: Synthesis, Molecular Structures, and pH‐Dependent Monomer–Dimer Interconversion in Solution
European Journal of Inorganic Chemistry, 2013Co-Authors: Yusuke Matsuki, Yuki Mouri, Yoshitaka Sakai, Satoshi Matsunaga, Kenji NomiyaAbstract:Powder and crystalline samples of the monomer (Et2NH2)5[α-PW11TiO40]·2H2O (EtN-1) and a crystalline sample of the μ-oxo dimer (Et2NH2)8[(α-PW11TiO39)2O]·6H2O (EtN-2) of mono-titanium(IV)-containing α-Keggin polyoxometalates (POMs) were prepared and characterized by elemental analysis, thermogravimetry/differential thermal analysis (TG/DTA), FTIR, single-crystal X-ray crystallography, and solid-state cross-polarization magic angle spinning (CPMAS) 31P NMR and solution (31P and 183W) NMR Spectroscopy. The molecular structure of the dimeric polyoxoanion with a μ-oxo group in 2 was determined for the first time. The monomer–dimer equilibrium in solution was clarified by pH-varied 31P NMR Spectroscopy.
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Encapsulation of Anion/Cation in the Central Cavity of Tetrameric Polyoxometalate, Composed of Four Trititanium(IV)‐Substituted α‐Dawson Subunits, Initiated by Protonation/Deprotonation of the Bridging Oxygen Atoms on the Intramolecular Surface.
ChemInform, 2011Co-Authors: Yoshitaka Sakai, Yusuke Matsuki, Satoshi Matsunaga, Shuji Ohta, Yukihiro Shintoyo, Shoko Yoshida, Yuhki Taguchi, Kenji NomiyaAbstract:The [(P2W15Ti3O60.5)4 (NH4)]35- Dawson tetramer with encapsulated NH4+ cation is synthesized and characterized by FTIR, 15N{1H}, 31P, and 183W NMR Spectroscopy.
Yoshitaka Sakai - One of the best experts on this subject based on the ideXlab platform.
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A first example of polyoxotungstate-based giant molecule. Synthesis and molecular structure of a tetrapod-shaped Ti–O–Ti bridged anhydride form of Dawson tri-titanium(IV)-substituted polyoxotungstate
Dalton Transactions, 2020Co-Authors: Yoshitaka Sakai, Chika Nozaki Kato, Kenji Yoza, Kenji NomiyaAbstract:The preparation and structural characterization of a giant “tetrapod”-shaped inorganic molecule, [(α-1,2,3-P2W15Ti3O60.5)4Cl]37− ,1a (abbreviated to {TiO6}12; FW ∼15700), consisting of four tri-TiIV-1,2,3-substituted α-Dawson substructures and one encapsulated Cl− ion, are described. A water-soluble, all-inorganic composition compound of the tetrameric Ti–O–Ti bridged anhydride form, NaxH33−xK4[1a]·yH2O, 1 (x = 21–26, y = 60–70), being afforded by a stoichiometric reaction in aqueous solution of tri-lacunary Dawson polyoxotungstate Na12[B-α-P2W15O56]·19H2O with 3 equiv of Ti(SO4)2·4H2O in HCl-acidic aqueous solution followed by exchanging the countercation, was obtained as analytically pure, homogeneous colorless plate crystals. Single-crystal X-ray structure analysis revealed that the polyoxoanion 1a was an inorganic, giant “tetrapod”-shaped molecule (described as a sphere with a diameter of ∼31.2 A) with approximately Td symmetry. Characterization of 1 was also accomplished by complete elemental analysis, TG/DTA, FTIR, UV-vis absorption and solution (31P and 183W) NMR Spectroscopy.
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Synthesis and pH-variable ultracentrifugation molecular weight measurements of the dimeric, Ti–O–Ti bridged anhydride form of a novel di-TiIV-1,2-substituted α-Keggin polyoxotungstate. Molecular structure of the [(α-1,2-PW10Ti2O39)2]10− polyoxoanion
Journal of The Chemical Society-dalton Transactions, 2020Co-Authors: Kenji Nomiya, Yoshitaka Sakai, Mizuto Takahashi, Jason A. Widegren, Takao Aizawa, Noriko Chikaraishi KasugaAbstract:The preparation and characterization of a Keggin-type, novel di-TiIV-1,2-substituted polyoxotungstate are described. The dimeric, Ti–O–Ti bridged anhydride form of the di-TiIV-1,2-substituted α-Keggin polyoxotungstate, K10[α,α-P2W20Ti4O78]·12H2O 1, was unexpectedly found in the varied molar-ratio reactions of tri-lacunary precursor Na9[A-PW9O34]·19H2O with Ti(SO4)2 in aqueous solution. Although this compound was first found as a minor product in the preparation of the dimeric, tri-TiIV-1,2,3-substituted species, K10H2[α,α-P2W18Ti6O77]·17H2O 3, it was successfully prepared as a main product in this work and structurally characterized. Compound 1, as analytically pure, homogeneous colorless needle crystals, was obtained as a major product in 29.2% yield (2.7 g scale) from recrystallization under acidic conditions (at pH 2.2) of the 1 ∶ 2 molar-ratio reaction product. X-Ray structure analysis revealed that the molecular structure of 1 consisted of a dimeric anhydride formed by two Ti–O–Ti bonds linking two [α-1,2-PW10Ti2O40]7− Keggin units. Interestingly, ultracentrifugation molecular weight (MW) measurements of this compound in aqueous solution showed the pH-dependent interconversion between monomer [α-1,2-PW10Ti2O40]7−2 and dimer [α,α-P2W20Ti4O78]10−1; this compound was present as the monomer under less acidic conditions (pH 7.8), while it was in dimeric form under more acidic conditions (pH 1.0 and 2.2). Characterization of 1 was also accomplished by complete elemental analyses, TG/DTA, FTIR and solution (31P and 183W) NMR Spectroscopy.
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Monomer and Dimer of Mono-titanium(IV)-Containing α-Keggin Polyoxometalates: Synthesis, Molecular Structures, and pH-Dependent Monomer—Dimer Interconversion in Solution.
ChemInform, 2013Co-Authors: Yusuke Matsuki, Yuki Mouri, Yoshitaka Sakai, Satoshi Matsunaga, Kenji NomiyaAbstract:Compounds (III) and (IV) are characterized by single crystal XRD, FTIR, CPMAS 31P NMR, and solution 31P and 183W NMR Spectroscopy.
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Monomer and Dimer of Mono‐titanium(IV)‐Containing α‐Keggin Polyoxometalates: Synthesis, Molecular Structures, and pH‐Dependent Monomer–Dimer Interconversion in Solution
European Journal of Inorganic Chemistry, 2013Co-Authors: Yusuke Matsuki, Yuki Mouri, Yoshitaka Sakai, Satoshi Matsunaga, Kenji NomiyaAbstract:Powder and crystalline samples of the monomer (Et2NH2)5[α-PW11TiO40]·2H2O (EtN-1) and a crystalline sample of the μ-oxo dimer (Et2NH2)8[(α-PW11TiO39)2O]·6H2O (EtN-2) of mono-titanium(IV)-containing α-Keggin polyoxometalates (POMs) were prepared and characterized by elemental analysis, thermogravimetry/differential thermal analysis (TG/DTA), FTIR, single-crystal X-ray crystallography, and solid-state cross-polarization magic angle spinning (CPMAS) 31P NMR and solution (31P and 183W) NMR Spectroscopy. The molecular structure of the dimeric polyoxoanion with a μ-oxo group in 2 was determined for the first time. The monomer–dimer equilibrium in solution was clarified by pH-varied 31P NMR Spectroscopy.
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Encapsulation of Anion/Cation in the Central Cavity of Tetrameric Polyoxometalate, Composed of Four Trititanium(IV)‐Substituted α‐Dawson Subunits, Initiated by Protonation/Deprotonation of the Bridging Oxygen Atoms on the Intramolecular Surface.
ChemInform, 2011Co-Authors: Yoshitaka Sakai, Yusuke Matsuki, Satoshi Matsunaga, Shuji Ohta, Yukihiro Shintoyo, Shoko Yoshida, Yuhki Taguchi, Kenji NomiyaAbstract:The [(P2W15Ti3O60.5)4 (NH4)]35- Dawson tetramer with encapsulated NH4+ cation is synthesized and characterized by FTIR, 15N{1H}, 31P, and 183W NMR Spectroscopy.
René Thouvenot - One of the best experts on this subject based on the ideXlab platform.
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Aryldiazenido derivatives: A new entry to the functionalization of Keggin polyoxometalates
Inorganica Chimica Acta, 2010Co-Authors: Carlos Bustos, Kamal Boubekeur, René Thouvenot, Anna Proust, Desmond Mac-leod Carey, Pierre GouzerhAbstract:Abstract A series of aryldiazenido polyoxomolybdates of the type (nBu4N)2[Mo5O13(OMe)4(NNAr){Na(MeOH)}] (Ar = C6F5, 1; Ar = O2N-o-C6H4, 2; Ar = O2N-m-C6H4, 3; Ar = O2N-p-C6H4, 4a; Ar = (O2N)2-o,p-C6H3, 5) have been obtained by controlled degradation of the parent compounds (nBu4N)3[Mo6O18(NNAr)] with NaOH in methanol. They have been characterized by elemental analysis and UV–Vis and IR Spectroscopy. In addition, 4a has been characterized by 95Mo NMR Spectroscopy and the crystal structure of (nBu4N)2[Mo5O13(OMe)4(NNC6H4-p-NO2){Na(H2O))]·H2O (4b) has been determined by X-ray diffraction. The molecular structure of the anion of 4b features a lacunary Lindqvist-type anion [Mo5O13(OMe)4(NNC6H4-p-NO2)]3− interacting with a sodium cation through the four terminal axial oxygen atoms. The 1:1 sodium complexes react with BaCl2 and BiCl3 to yield 2:1 complexes which have been isolated as (nBu4N)4[Ba{Mo5O13(OMe)4(NNAr)}2] (Ar = C6F5, 6; Ar = O2N-p-C6H4, 7) and (nBu4N)3[Bi{Mo5O13(OMe)4(NNAr)}2] (Ar = C6F5, 8; Ar = O2N-p-C6H4, 9). X-ray crystallography analysis of 9·Me2CO has shown that the tetradentate [Mo5O13(OMe)4(N2C6H4-p-NO2)]3− anions provide a square-antiprismatic environment for Bi. In contrast, IR Spectroscopy provides evidence for a square-prismatic environment of Ba in 6 and 7. In acetonitrile–methanol mixed solvent, [Mo5O13(OMe)4(NNAr)]3− and [PW11O39]7−, generated in situ by alkaline degradation of their respective parents, [Mo6O18(NNAr)]3− and [PW12O40]3−, react together to give the Keggin-type diazenido compounds (nBu4N)4[PW11O39(MoNNAr)] (Ar = O2N-o-C6H4, 10; Ar = O2N-m-C6H4, 11; Ar = O2N-p-C6H4, 12), which have been characterized by 31P and 183W NMR Spectroscopy.
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Synthesis and Spectroscopic Characterization of Organophosphono Derivatives of Lindqvist Niobotungstates – X‐ray Crystal Structures of (nBu4N)3[NbW10O38(RP)2] (R = nBu, Hep and Ph)
European Journal of Inorganic Chemistry, 2008Co-Authors: Hafedh Driss, Kamal Boubekeur, Mongi Debbabi, René ThouvenotAbstract:A series of organophosphonopolyoxoniobotungstates [NbW10O38(RP)2]3– {R = Me (1), Et (2), Pr (3), nBu (4), Hex (5), Hep (6), Cy (7), Ph (8), All (9)} has been prepared by the reaction of (nBu4N)3[NbW5O19] with the appropriate organophosphono dichloride, RP(O)Cl2. All of the products were characterized by infrared and multinuclear (31P and 183W) NMR Spectroscopy. Compounds 4, 6 and 8 were characterized by single-crystal X-ray diffraction. The hybrid anions [NbW10O38(RP)2]3– are made up of two W5O18 subunits, which can be viewed as monovacant derivatives of the niobotungstate precursor linked by a {Nb(OPR)2} group.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
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Synthesis and Characterization of the Keggin-Type Ruthenium-Nitrido Derivative [PW11O39{RuN}]4- and Evidence of Its Electrophilic Reactivity
Journal of the American Chemical Society, 2007Co-Authors: Vanina Lahootun, Kamal Boubekeur, René Thouvenot, Claire Besson, Richard Villanneau, Francoise Villain, Lise-marie Chamoreau, Sébastien Blanchard, Anna ProustAbstract:The ruthenium-nitrido POM derivative [PW11O39{RuVIN}]4- has been synthesized by reaction between [PW11O39]7- and [RuVINCl5]2- or [RuVINCl4]-. Its molecular structure has been confirmed from multinuclear 31P and 183W NMR Spectroscopy together with an EXAFS study, while the oxidation state of the ruthenium bearing the nitrido ligand has been inferred both from 183W NMR and XANES analysis at the Ru-K edge. The potential of [PW11O39{RuVIN}]4- in N-atom transfer reactions has been demonstrated through reaction with triphenylphosphine, which ultimately leads to the release of the bis(triphenylphosphane)iminium cation [PPh3NPPh3]+ through several intermediates, among which the phosphoraniminato derivative [PW11O39{RuVNPh3}]3- has been structurally characterized. Its unusual oxidation state is in accordance with its EPR spectrum.
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structural determination by x ray diffraction and 183W NMR Spectroscopy of mono substituted hexatungstates n c4h9 4n 3mw5o19 m nb v
Journal of Chemical Crystallography, 2006Co-Authors: F Bannani, Hafedh Driss, René Thouvenot, Mongi DebbabiAbstract:The tetrabutylammonium salt of mononiobotungstate [(n-C4H9)4N]3NbW5O19 (1) and the tetrabutylammonium salt of monovanadotungstate [(n-C4H9)4N]3VW5O19 (2) are isotypes; both crystallize in the monoclinic system, space group C2/c (N° 15) with Z=8. The cell parameters for 1 are a=30.4038(8) A, b=18.5948(8) A, c=27.3330(3) A, β=112.4555(6)°, V=14281.1(7) A3 and the final reliability factors are R=0.043 and R w=0.047 for 5801 reflections. The cell parameters for 2 are a=30.096(8) A, b=18.373(3) A, c= 27.201(6) A, β=112.402(14)°, V=13906(5) A3 and the final reliability factors are R=0.048 and R w=0.054 for 6122 reflections. Both anions, [NbW5O19] 3− and [VW5O19] 3− exhibit the Lindqvist structure of the parent hexatungstate anion. The six metal positions are disordered and for each metal site the occupation factor is close to 1/6 M (M=Nb, V) and 5/6 W. Furthermore the two compounds were characterized by IR in the solid state, and 183W solution NMR. The 183W spectrum of [NbW5O19] 3− presents two resonances with relative intensities 4:1 in agreement with the C4v symmetry of the anion.
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Structural determination by X-Ray diffraction and 183W NMR Spectroscopy of mono substituted hexatungstates [(n-C4H9)4N]3MW5O19 (M = Nb, V)
Journal of Chemical Crystallography, 2006Co-Authors: F Bannani, Hafedh Driss, René Thouvenot, Mongi DebbabiAbstract:The tetrabutylammonium salt of mononiobotungstate [(n-C4H9)4N]3NbW5O19 (1) and the tetrabutylammonium salt of monovanadotungstate [(n-C4H9)4N]3VW5O19 (2) are isotypes; both crystallize in the monoclinic system, space group C2/c (N° 15) with Z=8. The cell parameters for 1 are a=30.4038(8) A, b=18.5948(8) A, c=27.3330(3) A, β=112.4555(6)°, V=14281.1(7) A3 and the final reliability factors are R=0.043 and R w=0.047 for 5801 reflections. The cell parameters for 2 are a=30.096(8) A, b=18.373(3) A, c= 27.201(6) A, β=112.402(14)°, V=13906(5) A3 and the final reliability factors are R=0.048 and R w=0.054 for 6122 reflections. Both anions, [NbW5O19] 3− and [VW5O19] 3− exhibit the Lindqvist structure of the parent hexatungstate anion. The six metal positions are disordered and for each metal site the occupation factor is close to 1/6 M (M=Nb, V) and 5/6 W. Furthermore the two compounds were characterized by IR in the solid state, and 183W solution NMR. The 183W spectrum of [NbW5O19] 3− presents two resonances with relative intensities 4:1 in agreement with the C4v symmetry of the anion.
Yusuke Matsuki - One of the best experts on this subject based on the ideXlab platform.
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Monomer and Dimer of Mono-titanium(IV)-Containing α-Keggin Polyoxometalates: Synthesis, Molecular Structures, and pH-Dependent Monomer—Dimer Interconversion in Solution.
ChemInform, 2013Co-Authors: Yusuke Matsuki, Yuki Mouri, Yoshitaka Sakai, Satoshi Matsunaga, Kenji NomiyaAbstract:Compounds (III) and (IV) are characterized by single crystal XRD, FTIR, CPMAS 31P NMR, and solution 31P and 183W NMR Spectroscopy.
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Monomer and Dimer of Mono‐titanium(IV)‐Containing α‐Keggin Polyoxometalates: Synthesis, Molecular Structures, and pH‐Dependent Monomer–Dimer Interconversion in Solution
European Journal of Inorganic Chemistry, 2013Co-Authors: Yusuke Matsuki, Yuki Mouri, Yoshitaka Sakai, Satoshi Matsunaga, Kenji NomiyaAbstract:Powder and crystalline samples of the monomer (Et2NH2)5[α-PW11TiO40]·2H2O (EtN-1) and a crystalline sample of the μ-oxo dimer (Et2NH2)8[(α-PW11TiO39)2O]·6H2O (EtN-2) of mono-titanium(IV)-containing α-Keggin polyoxometalates (POMs) were prepared and characterized by elemental analysis, thermogravimetry/differential thermal analysis (TG/DTA), FTIR, single-crystal X-ray crystallography, and solid-state cross-polarization magic angle spinning (CPMAS) 31P NMR and solution (31P and 183W) NMR Spectroscopy. The molecular structure of the dimeric polyoxoanion with a μ-oxo group in 2 was determined for the first time. The monomer–dimer equilibrium in solution was clarified by pH-varied 31P NMR Spectroscopy.
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Encapsulation of Anion/Cation in the Central Cavity of Tetrameric Polyoxometalate, Composed of Four Trititanium(IV)‐Substituted α‐Dawson Subunits, Initiated by Protonation/Deprotonation of the Bridging Oxygen Atoms on the Intramolecular Surface.
ChemInform, 2011Co-Authors: Yoshitaka Sakai, Yusuke Matsuki, Satoshi Matsunaga, Shuji Ohta, Yukihiro Shintoyo, Shoko Yoshida, Yuhki Taguchi, Kenji NomiyaAbstract:The [(P2W15Ti3O60.5)4 (NH4)]35- Dawson tetramer with encapsulated NH4+ cation is synthesized and characterized by FTIR, 15N{1H}, 31P, and 183W NMR Spectroscopy.
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Encapsulation of Anion/Cation in the Central Cavity of Tetrameric Polyoxometalate, Composed of Four Trititanium(IV)-Substituted α-Dawson Subunits, Initiated by Protonation/Deprotonation of the Bridging Oxygen Atoms on the Intramolecular Surface
Inorganic Chemistry, 2011Co-Authors: Yoshitaka Sakai, Yusuke Matsuki, Satoshi Matsunaga, Shuji Ohta, Yukihiro Shintoyo, Shoko Yoshida, Yuhki Taguchi, Kenji NomiyaAbstract:Preparation and structural characterization of a novel polyoxometalate (POM), [(P2W15Ti3O60.5)4(NH4)]35-1, i.e., an encapsulated NH4+ cation species in the central cavity of a tetramer (called the Dawson tetramer) constituted by trititanium(IV)-substituted α-Dawson POM substructure, are described. POM 1 was synthesized by several different methods and unequivocally characterized by complete elemental analysis, thermogravimetric and differential thermal analysis (TG/DTA), FTIR Spectroscopy, solution (15N{1H}, 31P, 183W) NMR Spectroscopy, and X-ray crystallography. First, POM 1 was synthesized by a reaction of NH4Cl in aqueous solution with a precursor, which was derived by thermal treatment of a monomeric triperoxotitanium(IV)-substituted Dawson POM, [α-1,2,3-P2W15(TiO2)3O56(OH)3]9-2, for 3 h in an electric furnace at 200 °C. The encapsulated NH4+ cation in 1 was confirmed by 15N{1H} NMR measurement and X-ray crystallography. As another synthesis of 1, a direct exchange of the Cl– anion encapsulated in [{α...
Lynn C. Francesconi - One of the best experts on this subject based on the ideXlab platform.
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Lanthanide Complexes of [α-2-P2W17O61]10-: Solid State and Solution Studies
Inorganic Chemistry, 2002Co-Authors: Robertha C. Howell, Judit Bartis, Michaela Dankova, William Dew. Horrocks, And Arnold L. Rheingold, Lynn C. FrancesconiAbstract:We have isolated the 1:1 Ln:[α-2-P2W17O61]10- complexes for a series of lanthanides. The single-crystal X-ray structure of the Eu3+ analogue reveals two identical [Eu(H2O)3(α-2-P2W17O61)]7- moieties connected through two Eu−O−W bonds, one from each polyoxometalate unit. An inversion center relates the two polyoxometalate units. The Eu(III) ion is substituted for a [WO]4+ unit in the “cap” region of the tungsten−oxygen framework of the parent Wells−Dawson ion. The point group of the dimeric molecule is Ci. The extended structure is composed of the [Eu(H2O)3(α-2-P2W17O61)]214- anions linked together by surface-bound potassium cations. The space group is P1, a = 12.7214(5) A, b = 14.7402(7) A, c = 22.6724(9) A, α = 71.550(3)°, β = 84.019(3)°, γ = 74.383(3)°, V = 3883.2(3) A3, Z = 1. The solution studies, including 183W NMR Spectroscopy and luminescence lifetime measurements, show that the molecules dissociate in solution to form monomeric [Ln(H2O)4(α-2-P2W17O61)]7- species.
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Synthesis and characterization of ReV, ReVI and ReVII complexes of the [α2-P2W17O61]10– isomer
Journal of The Chemical Society-dalton Transactions, 1999Co-Authors: Anne Venturelli, Mark J. Nilges, Alex I. Smirnov, R. L. Belford, Lynn C. FrancesconiAbstract:Rhenium-(V), -(VI) and -(VII) complexes of the [α2-P2W17O61]10– isomer, a mono-lacunary derivative of the [α-P2W18O62]6– (Wells–Dawson) ion have been prepared and characterized by multinuclear NMR Spectroscopy, electrospray mass spectrometry and electron paramagnetic resonance Spectroscopy, among other techniques. The molecules have the formulation [α2-ReOP2W17O61]n–, where n = 7,6,5 for ReV, ReVI and ReVII, respectively. 183W NMR Spectroscopy for the ReV and ReVII analogs shows that the molecules have Cs symmetry, as expected for substitution in the α2 site. Simulations of the X-band and Q-band EPR spectra of the ReVI analog, using Cs symmetry, allow determination of the g, hyperfine and quadrupole coupling tensors. X-Band, Q-band and W-band EPR Spectroscopy show extreme variations in linewidths due to random strains or distortions of the complex.
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Preparation and Tungsten-183 NMR Characterization of [α-1-P2W17O61]10-, [α-1-Zn(H2O)P2W17O61]8-, and [α-2-Zn(H2O)P2W17O61]8-
Inorganic Chemistry, 1996Co-Authors: Judit Bartis, Yuliya Kunina, And Michael Blumenstein, Lynn C. FrancesconiAbstract:The preparation of the α-1 and α-2 isomers of the Wells−Dawson 17 tungsto derivatives by standard methods is accompanied by a significant proportion of the other isomer present as an impurity. In this study, the α-1 and α-2 isomers of [Zn(H2O)P2W17O61]8- have been prepared in >98% purity by reacting isomerically pure K9Li[α-1-P2W17O61] and K10[α-2-P2W17O61], respectively, with ZnCl2, while rigorously controlling the pH at 4.7. The molecules were isolated as potassium salts. For 183W NMR and 31P NMR characterization, both molecules were ion exchanged by cation-exchange chromatography, maintaining the pH at 4.7, to obtain the lithium salts. Removal of water and isolation of a solid sample of [α-1-Zn(H2O)P2W17O61]8- was achieved by lyophilization at −40 °C. The chemical shift data from 31P and 183W NMR Spectroscopy of the isolated [α-1-Zn(H2O)P2W17O61]8- and [α-2-Zn(H2O)P2W17O61]8- isomers are consistent with a mixture of the α-1 and α-2 isomers reported previously;1 the molecules have the expected C1 and Cs...
