- Thermal and calorimetric investigations on beryllium periodate hydrates
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The thermal decompositions of two beryllium periodate hydrates, Be(IO4)2·8H2O and Be(H4IO6)2·2H2O, were studied by DTA and TG in the temperature range from 298 to 1073 K, and by DSC from 298 to 723 K. The intermediates of the thermal decompositions were identified via quantitative analysis, IR spectroscopy and the TG curves. The data obtained were utilized to suggest a scheme for the thermal decompositions of the two periodates. Both compounds decompose via an anhydrous beryllium iodate, and the final residue is beryllium oxide. The enthalpies of the phase transitions were determined from the DSC curves.
- Maneva,Georgiev,Pavlova
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- Fluorine-oxygen exchange reactions in IF5, IF7, and IF5O
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When reacted with alkali-metal nitrates, IF5 readily exchanges two fluorine ligands for a doubly bonded oxygen atom. In all cases MIF4O salts (M = Li, K, Cs) and FNO2 are formed as the primary products. The FNO2 byproduct undergoes a fast secondary reaction with MNO3 to yield equimolar amounts of N2O5 and MF. The N2O5 decomposes to N2O4 and 0.5 mol of O2, while the MF, depending on the nature of M, does or does not undergo complexation with the excess of IF5. Pure MIF4O salts, free of MF or MF·nIF5 byproducts, were prepared from MF, I2O5, and IF5 in either CH3CN or IF5 as a solvent. The new compounds LiIF4O, NaIF4O, RbIF4O, and NOIF4O were characterized by vibrational spectroscopy. It was also shown that, contrary to a previous report, FNO2 does not form a stable adduct with IF5 at temperatures as low as -78°C. An excess of IF7 reacts with MNO3 (M = Li, Na) to give MF, FNO2, IF5, and 0.5 mol of O2, but surprisingly no IF5O. With CsNO3, the reaction products are analogous, except for the CsF reacting with both the IF5 product and the excess of IF7 to give CsIF6·2IF5 and CsIF8, respectively. When in the IF7 reaction an excess of LiNO3, is used, the IF5 product undergoes further reaction with LiNO3, as described above. The IF5O molecule was found to be rather unreactive. It does not react with either LiF or CsF at 25 or 60°C or with LiNO3 or CsNO3 at 25°C. At 60°C with LiNO3, it slowly loses oxygen, with the IF5 product reacting to yield LiIF4O, as described above.
- Christe, Karl O.,Wilson, William W.,Wilson, Richard D.
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p. 904 - 908
(2008/10/08)
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