- Zirconium(IV) and hafnium(IV) coordination polymers with a tetra-acetyl-ethane (Bisacac) ligand: Synthesis, structure elucidation and gas sorption behavior
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Octahedrally shaped crystals of Zr(Bisacac)2 and Hf(Bisacac)2, M(IV) derivatives of bis-acetylacetone (tetra-acetyl-ethane), H2Bisacac, were obtained in quantitative yield by a simple and reproducible synthetic procedure. The coordination spheres of Zr and Hf were found to be very closely related to those in molecular beta-diketonates, M(acac)4, according to the data of EXAFS spectroscopy. The structures are highly disordered, reflecting the multitude of conformations possible for each M(IV) centre. Crystal structure models involving metal centres with tetrahedrally arranged binding nodes were proposed for M(Bisacac)2. The produced materials are microporous with pronounced temperature-dependent affinity and selectivity to hydrogen gas absorption.
- Hentschel, Felix,Vinogradov, Vladimir V.,Vinogradov, Alexandr V.,Agafonov, Alexander V.,Guliants, Vadim V.,Persson, Ingmar,Seisenbaeva, Gulaim A.,Kessler, Vadim G.
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- Stabilization and destabilization of zirconium propoxide precursors by acetylacetone
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The stabilizing and destabilizing mechanism in the action of acetylacetone on zirconium propoxide precursors is revealed; the nature of heteroleptic intermediates provides an explanation.
- Spijksma, Gerald I.,Bouwmeester, Henny J. M.,Blank, Dave H. A.,Kessler, Vadim G.
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- Gas-sensing properties of nanostructured CeO2-xZrO2 thin films obtained by the sol-gel method
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With the use of sol-gel technology and heat-treatment at a temperature of 500°С we obtained CeO2-xZrO2 (where х = 0, 5, 10, 20, 30, 50 mol%) powders and thin films that are promising for oxygen detection. A phase composition of the samples was studied using XRD and Raman spectroscopy. It was shown that under these synthesis conditions, both for powders and films, an increase in the content of zirconium dioxide from 0 to 50 mol% entailed the formation of solid solutions with a fluorite crystal lattice in the structure of cerium dioxide. For CeO2-xZrO2 thin films (where х = 0÷30 mol%), gas-sensing properties were studied: we identified a resistive response to oxygen in a wide range of concentrations (0.4–20%) at a low operating temperature of 400 °C, and studied the effect of moisture on the signal obtained while detecting O2. Upon increase of humidity from 0 to 100% resistance and response to oxygen values decrease, and from 75% and larger humidity a significant worsening of kinetic properties occurs, such as response time and recovery time. Selectivity to analyte gases such as H2, CO, CH4, NO2 was studied. The best selectivity to oxygen was displayed by the film containing 20% ZrO2, while the film with 10% ZrO2 demonstrated the worst selectivity. Using Raman spectroscopy it was shown that, after studies in a gas-air mixture containing not more than 1% of reducing gases, the nanomaterial surface contained oxygen superoxides and peroxides that were not removed, even after subsequent heat treatment in air at 500 °C.
- Mokrushin, Artem S.,Simonenko, Elizaveta P.,Simonenko, Nikolay P.,Bukunov, Kirill A.,Sevastyanov, Vladimir G.,Kuznetsov, Nikolay T.
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- Steam treatment of metal acetylacetonate and ethyl acetoacetate complexes at 90 °C for preparation of metal oxides
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Steam treatment is a technique for synthesizing metal oxides via the exposure of metal complexes to water vapor at low temperatures (2(OiPr)2, Ti(etac)2(OiPr)2, Fe(acac)3, Co(acac)2, Co(etac)2, and Cu(etac)2 were transformed to crystalline metal oxides upon the steam treatment under air atmosphere. Other metal complexes were transformed to noncrystalline metal oxides, metal hydroxides, metal carbonates, or no decomposition. Hydrolysis mechanism of steam treatment proceeds by water attacking metal species. The formed reactive hydroxy group was quickly reacted to other molecules, and metalloxane bonding was formed.
- Gunji, Takahiro,Hayami, Ryohei,Iida, Yoshito,Sato, Yohei
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supporting information
(2022/02/23)
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- Synthesis, structural characterization, and catalytic properties of group 4 metal complexes incorporating a phosphorus-bridged indenyl-carboranyl constrained-geometry ligand
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Interaction of iPr2NP(C9H 7)(C2B10H11) with 1 equiv of M(NR2)4 in toluene gave constrained-geometry group 4 metal amides [η5:σ-iPr2NP(C 9H6)(C2B10H10)]M(NMe 2)2 (R = Me, M = Ti (1), Zr (2), Hf (3); R = Et, M = Hf (4)) in good yields. Compound 2 reacted with 3 equiv of PhNCO to produce the tri-insertion product [η5:σ-iPr 2NP(C9H6)(C2B10H 10)]Zr[η2-OC(NMe2)NPh] [η 2-OC(NMe2)N(Ph)C=(NPh)O] (5). No further insertion reaction occurred with another equivalent of PhNCO. Instead, the trimer (PhNCO)3 was isolated. Compound 2 reacted with 2 equiv of n-BuLi in toluene to afford, after recrystallization from DME/toluene, the dilithium salt [Li(DME)3] [η5:σ-iPr 2NP(C9H6)(C2B10H 10)Li(DME)] (6). An equimolar reaction of 2 with acetylacetone resulted in the formation of Zr(acac)4. 2 exhibited an ethylene polymerization activity of 3.7 × 103 g PE mol-1 atm-1 h-1 upon activation with MMAO. Furthermore, 2 was also able to efficiently initiate the polymerization of ε-caprolactone to give polymers of high molecular weights (Mn > 40 000) and low polydispersities (MwMn 1.4) through the action of the nucleophilic amido-nitrogen atom, which represents the first example of the polymerization of ε-caprolactone catalyzed by group 4 metal amides.
- Wang, Hong,Chan, Hoi-Shan,Okuda, Jun,Xie, Zuowei
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p. 3118 - 3124
(2008/10/09)
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- Enthalpies of Fusion of Aluminium(III), Chronium(III), Zirconium(IV), and Zinc(II) Acetylacetonates
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The melting points and enthalpies of fusion of aluminium(III), chromium(III), zirconium(IV), and zinc(II) acetylacetonates have been measured by differential scanning calorimetry.
- Grinberg, Ya. Kh.,Lazarev, V. B.,Zavernyaev, A. Yu.,Shreider, V. A.,Chepik, S. D.
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p. 630 - 631
(2007/10/02)
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- HIGHLY VOLATILE beta -DIKETONATE COMPLEXES OF Zr(IV) AND Hf(IV).
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The synthesis was described and the behavior was investigated of complexes of Zr(IV) and Hf(IV) with pentanedione-2,4, 1,1,1,-trifluoropentanedione-2,4, and 2,2,6,6-tetramethylpentanedione-3,5 in the gas phase. The mechanism of thermal decomposition of the complexes was examined on the basis of a thermal analysis and IR spectroscopy. Heats of evaporation were determined by the gas chromatographic method and entropy effects of evaporation of the synthesized complexes were calculated.
- Volkov,Miropol'skaya,Mel'nikova,Mazurenko
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