Details
| Original language | English |
|---|---|
| Pages (from-to) | 1321-1329 |
| Number of pages | 9 |
| Journal | ZAAC ‐ Journal of Inorganic and General Chemistry |
| Volume | 619 |
| Issue number | 7 |
| Publication status | Published - Jul 1993 |
| Externally published | Yes |
Abstract
Crystalline sodium aluminogermanate hydroxosodalite hydrate Na6+x[Al6Ge6O24](OH)x · nH2O with x ≈ 1.6 and n ≈ 3.0 has been synthesized by reacting Al2O3, GeO2 and NaOH solution under hydrothermal conditions, and characterized by means of simultaneous thermal analysis, differential scanning calorimetry, X‐ray and neutron diffraction as well as 1H and 23Na MAS NMR and IR spectroscopy. The material undergoes a reversible structural phase transition at Tc = 166 K (heating mode), which is actually a complex two‐step transformation as detected in DSC measurements. Structure refinements of the cubic high‐temperature form (cell constant a = 9.034(2) Å, room temperature) with single‐crystal X‐ray and powder neutron diffraction data have not yielded overall satisfactory results, probably due to the solid‐solution character of the hydrosodalite. The refinements nevertheless demonstrate that (i) the sodalite host framework is a strictly alternating array of corner‐linked AlO4 and GeO4 tetrahedra, and (ii) most polyhedral [4668] cavities are occupied by four sodium cations and one orientationally disordered hydrogen dihydroxide anion, H3O2−, which possesses a strong central hydrogen bond. Variable‐temperature 1H MAS NMR spectra unambiguously confirm the presence of H3O2− ions and, in addition, reveal a dynamical intraionic exchange between the central and terminal protons and a rotational diffusion of those anions to occur in the high‐temperature form. The nature of the guest complexes filling the remaining cages could not be unambiguously determined. Results are compared with those obtained in recent studies on the related sodium aluminosilicate hydrosodalite system of the general formula Na6+x[Al6Si6O24] (OH)x · nH2O.
Keywords
- crystal structure, dynamical proton exchange, hydrogen dihydroxide anion, MAS NMR, phase transition, sodalite, Sodium aluminogermanate
ASJC Scopus subject areas
- Chemistry(all)
- Inorganic Chemistry
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In: ZAAC ‐ Journal of Inorganic and General Chemistry, Vol. 619, No. 7, 07.1993, p. 1321-1329.
Research output: Contribution to journal › Article › Research › peer review
}
TY - JOUR
T1 - Sodium aluminogermanate hydroxosodalite hydrate Na6+x[Al6Ge6O24](OH)x · nH2O (x ≈ 1.6, n ≈ 3.0)
T2 - Synthesis, phase transitions and dynamical disorder of the hydrogen dihydroxide anion, H3O2−, in the Cubic high‐temperature form
AU - Wiebcke, Michael
AU - Sieger, Peter
AU - Felsche, Jürgen
AU - Engelhardt, Günter
AU - Behrens, Peter
AU - Schefer, Jürg
PY - 1993/7
Y1 - 1993/7
N2 - Crystalline sodium aluminogermanate hydroxosodalite hydrate Na6+x[Al6Ge6O24](OH)x · nH2O with x ≈ 1.6 and n ≈ 3.0 has been synthesized by reacting Al2O3, GeO2 and NaOH solution under hydrothermal conditions, and characterized by means of simultaneous thermal analysis, differential scanning calorimetry, X‐ray and neutron diffraction as well as 1H and 23Na MAS NMR and IR spectroscopy. The material undergoes a reversible structural phase transition at Tc = 166 K (heating mode), which is actually a complex two‐step transformation as detected in DSC measurements. Structure refinements of the cubic high‐temperature form (cell constant a = 9.034(2) Å, room temperature) with single‐crystal X‐ray and powder neutron diffraction data have not yielded overall satisfactory results, probably due to the solid‐solution character of the hydrosodalite. The refinements nevertheless demonstrate that (i) the sodalite host framework is a strictly alternating array of corner‐linked AlO4 and GeO4 tetrahedra, and (ii) most polyhedral [4668] cavities are occupied by four sodium cations and one orientationally disordered hydrogen dihydroxide anion, H3O2−, which possesses a strong central hydrogen bond. Variable‐temperature 1H MAS NMR spectra unambiguously confirm the presence of H3O2− ions and, in addition, reveal a dynamical intraionic exchange between the central and terminal protons and a rotational diffusion of those anions to occur in the high‐temperature form. The nature of the guest complexes filling the remaining cages could not be unambiguously determined. Results are compared with those obtained in recent studies on the related sodium aluminosilicate hydrosodalite system of the general formula Na6+x[Al6Si6O24] (OH)x · nH2O.
AB - Crystalline sodium aluminogermanate hydroxosodalite hydrate Na6+x[Al6Ge6O24](OH)x · nH2O with x ≈ 1.6 and n ≈ 3.0 has been synthesized by reacting Al2O3, GeO2 and NaOH solution under hydrothermal conditions, and characterized by means of simultaneous thermal analysis, differential scanning calorimetry, X‐ray and neutron diffraction as well as 1H and 23Na MAS NMR and IR spectroscopy. The material undergoes a reversible structural phase transition at Tc = 166 K (heating mode), which is actually a complex two‐step transformation as detected in DSC measurements. Structure refinements of the cubic high‐temperature form (cell constant a = 9.034(2) Å, room temperature) with single‐crystal X‐ray and powder neutron diffraction data have not yielded overall satisfactory results, probably due to the solid‐solution character of the hydrosodalite. The refinements nevertheless demonstrate that (i) the sodalite host framework is a strictly alternating array of corner‐linked AlO4 and GeO4 tetrahedra, and (ii) most polyhedral [4668] cavities are occupied by four sodium cations and one orientationally disordered hydrogen dihydroxide anion, H3O2−, which possesses a strong central hydrogen bond. Variable‐temperature 1H MAS NMR spectra unambiguously confirm the presence of H3O2− ions and, in addition, reveal a dynamical intraionic exchange between the central and terminal protons and a rotational diffusion of those anions to occur in the high‐temperature form. The nature of the guest complexes filling the remaining cages could not be unambiguously determined. Results are compared with those obtained in recent studies on the related sodium aluminosilicate hydrosodalite system of the general formula Na6+x[Al6Si6O24] (OH)x · nH2O.
KW - crystal structure
KW - dynamical proton exchange
KW - hydrogen dihydroxide anion
KW - MAS NMR
KW - phase transition
KW - sodalite
KW - Sodium aluminogermanate
UR - http://www.scopus.com/inward/record.url?scp=0007981923&partnerID=8YFLogxK
U2 - 10.1002/zaac.19936190728
DO - 10.1002/zaac.19936190728
M3 - Article
AN - SCOPUS:0007981923
VL - 619
SP - 1321
EP - 1329
JO - ZAAC ‐ Journal of Inorganic and General Chemistry
JF - ZAAC ‐ Journal of Inorganic and General Chemistry
SN - 0044-2313
IS - 7
ER -