H-Bonding Dependent Structures of (NH4+)3H+(SO42-)2. Mechanisms of Phase Transitions
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- 作者：Paulina M. Dominiak ; Joanna Herold ; Waclaw Kolodziejski ; and Krzysztof Wo
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- 刊名：Inorganic Chemistry
- 出版年：2003
- 出版时间：March 10, 2003
- 年：2003
- 卷：42
- 期：5
- 页码：1590 - 1598
- 全文大小：495K
- 年卷期：v.42,no.5(March 10, 2003)
- ISSN：1520-510X
文摘
The role of different H-bonds in phases II, III, IV, and V of triammonium hydrogen disulfate, (NH4+)3H+(SO42-)2, hasbeen studied by X-ray diffraction and 1H solid-state MAS NMR. The proper space group for phase II is C2/c, forphases III and IV is P2/n, and for phase V is P 
. The structures of phases III and IV seem to be the same. Thehydrogen atom participating in the O--H+···O- H-bond in phase II of (NH4+)3H+(SO42-)2 at room temperature issplit at two positions around the center of the crucial O--H+···O- H-bonding, joining two SO42- tetrahedra. Withdecreasing temperature, it becomes localized at one of the oxygen atoms. Further cooling causes additionaldifferentiation of possibly equivalent sulfate dimers. The NH4+ ions participate mainly in bifurcated H-bonds withtwo oxygen atoms from sulfate anions. On cooling, the major contribution of the bifurcated H-bond becomes stronger,whereas the minor one becomes weaker. This is coupled with rotation of sulfate ions. In all the phases of(NH4+)3H+(SO42-)2, some additional, weak but significant, reflections are observed. They are located between thelayers of the reciprocal lattice, suggesting possible modulation of the host (NH4+)3H+(SO42-)2 structure(s). Accordingto 1H MAS NMR obtained for phases II and III, the nature of the acidic proton disorder is dynamic, and localizationof the proton takes place in a broader range of temperatures, as can be expected from the X-ray diffraction data.
. The structures of phases III and IV seem to be the same. Thehydrogen atom participating in the O--H+···O- H-bond in phase II of (NH4+)3H+(SO42-)2 at room temperature issplit at two positions around the center of the crucial O--H+···O- H-bonding, joining two SO42- tetrahedra. Withdecreasing temperature, it becomes localized at one of the oxygen atoms. Further cooling causes additionaldifferentiation of possibly equivalent sulfate dimers. The NH4+ ions participate mainly in bifurcated H-bonds withtwo oxygen atoms from sulfate anions. On cooling, the major contribution of the bifurcated H-bond becomes stronger,whereas the minor one becomes weaker. This is coupled with rotation of sulfate ions. In all the phases of(NH4+)3H+(SO42-)2, some additional, weak but significant, reflections are observed. They are located between thelayers of the reciprocal lattice, suggesting possible modulation of the host (NH4+)3H+(SO42-)2 structure(s). Accordingto 1H MAS NMR obtained for phases II and III, the nature of the acidic proton disorder is dynamic, and localizationof the proton takes place in a broader range of temperatures, as can be expected from the X-ray diffraction data.