- Tetraalkylammonium Salts of Platinum Nitrato Complexes: Isolation, Structure, and Relevance to the Preparation of PtOx/CeO2 Catalysts for Lowerature CO Oxidation
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A series of tetraalkylammonium salts with anionic platinum nitrato complexes (Me4N)2[Pt2(μ-OH)2(NO3)8] (1), (Et4N)2[Pt2(μ-OH)2(NO3)8] (2), (n-Pr4N)2[Pt2(μ-OH)2(NO3)8] (3b), (n-Pr4N)2[Pt(NO3)6] (3a), and (n-Bu4N)2[Pt(NO3)6] (4) were isolated from nitric acid solutions of [Pt(H2O)2(OH)4] in high yield. The structures of salts 2, 3a, 3b, and 4, prepared for the first time, were characterized by X-ray diffraction. The sorption of [Pt(NO3)6]2- and [Pt2(μ-OH)2(NO3)8]2- complexes onto the ceria surface from acetone solutions of salts 4 and 1 was examined. The dimeric anion was shown to quickly and irreversibly chemisorb onto the CeO2 carrier, selectively transforming into Pt(II) centers after thermal treatment, becoming active in the lowerature CO oxidation reaction (T50% = 110 °C at a space velocity of 240 000 h-1). By contrast, the homoleptic complex [Pt(NO3)6]2- did not interact with the ceria, which may be attributed to the substitutional inertness of the [Pt(NO3)6]2- anion. We believe that the strategy based on the sorption of polynuclear platinum nitrato complexes is an effective route to prepare ionic platinum species uniformly distributed on an oxide carrier for various catalytic applications.
- Vasilchenko, Danila,Topchiyan, Polina,Berdyugin, Semen,Filatov, Evgeny,Tkachev, Sergey,Baidina, Iraida,Komarov, Vladislav,Slavinskaya, Elena,Stadnichenko, Andrey,Gerasimov, Evgeny
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- A calorimetric study of the hydrolysis and peroxide complex formation of the uranyl(vi) ion
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The enthalpies of reaction for the formation of uranyl(vi) hydroxide {[(UO2)2(OH)2]2+, [(UO 2)3(OH)4]2+, [(UO2) 3(OH)5]+, [(UO2)3(OH) 6](aq), [(UO2)3(OH) 7]-, [(UO2)3(OH)8] 2-, [(UO2)(OH)3]-, [(UO 2)(OH)4]2-} and peroxide complexes {[UO 2(O2)(OH)]- and [(UO2) 2(O2)2(OH)]-} have been determined from calorimetric titrations at 25 °C in a 0.100 M tetramethyl ammonium nitrate ionic medium. The hydroxide data have been used to test the consistency of the extensive thermodynamic database published by the Nuclear Energy Agency (I. Grenthe, J. Fuger, R. J. M. Konings, R. J. Lemire, A. B. Mueller, C. Nguyen-Trung and H. Wanner, Chemical Thermodynamics of Uranium, North-Holland, Amsterdam, 1992 and R. Guillaumont, T. Fanghaenel, J. Fuger, I. Grenthe, V. Neck, D. J. Palmer and M. R. Rand, Update on the Chemical Thermodynamics of Uranium, Neptunium, Plutonium, Americium and Technetium, Elsevier, Amsterdam, 2003). A brief discussion is given about a possible structural relationship between the trinuclear complexes [(UO2)3(OH) n]6-n, n = 4-8.
- Zanonato, Pier Luigi,Di Bernardo, Plinio,Grenthe, Ingmar
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p. 2378 - 2383
(2014/02/14)
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- Alkylation of ammonium salts catalyzed by imidazolium-based ionic liquid catalysts
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Quaternary ammonium salts were synthesized from ammonium salts and dialkyl carbonates over imidazolium ionic liquid catalysts. The reaction gave almost stoichiometric amounts of the quaternary ammonium salts for halides and nitrates. It was found that the electron-donating property of the alkyl moieties of ammonium cations, the electrophilic nature of the alkyl group of the carbonate, the acidity of the acid that the anion of the ammonium salt corresponds to, and the steric hindrance of the ammonium salts and the dialkyl carbonates are the key factors that influence the yields of quaternary ammonium salts. Strong electron-donating alkyl groups on the nitrogen atom of the ammonium salt, electron-withdrawing groups on the methylene carbon of dialkyl carbonate, and weaker steric hindrance of the starting ammonium salts and dialkyl carbonates favor the alkylation reaction of ammonium salts.
- Zheng, Zhuo Qun,Wang, Jie,Wu, Ting Hua,Zhou, Xiao Ping
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p. 1095 - 1101
(2008/03/27)
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- The synthesis of quaternary ammonium salts from ammonium salts and dialkyl carbonate
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Quaternary ammonium salts were synthesized from ammonium salts and dialkyl carbonates over an ionic liquid catalyst 1-ethyl-3-methylimidazolium bromide. The Royal Society of Chemistry 2006.
- Zheng, Zhuoqun,Wu, Tinghua,Zhou, Xiaoping
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p. 1864 - 1865
(2008/03/14)
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- Thermochemistry of Polyhalides. Part 5. Standard Enthalpies of Formation of Tetramethylammonium and Tetraethylammonium Tetrachloroiodates
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The standard enthalpies of formation of methyl- and ethyl-ammonium tetrachloroiodates NRnH4-nICl4 (R = Me or Et, 0 /= n /= 4), have been determined by a solution reaction method using aqueous silver nitrate.Lattice energies have been estimated from these data and trends in these and in the standard enthalpies of formation as a function of alkyl substitution are discussed.
- Derakhshan, B. Mokhtar,Finch, Arthur,Gates, Peter N.,Stephens, Michael
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p. 997 - 1000
(2007/10/02)
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