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Xenon hexafluoride: structural crystallography of tetrameric phases
Science (New York, N.Y.)
|February 5, 1971
Summary
Xenon hexafluoride exhibits three crystalline phases with unique structures. Transitions between these phases involve significant structural changes and ordering of molecular configurations.
Area of Science:
- Solid-state chemistry
- Inorganic chemistry
- Crystallography
Background:
- Xenon hexafluoride (XeF6) exists in multiple crystalline forms.
- Understanding these phases is crucial for predicting its behavior under varying conditions.
Purpose of the Study:
- To elucidate the structural characteristics of three crystalline phases of xenon hexafluoride.
- To describe the transformations between these phases and the underlying mechanisms.
Main Methods:
- X-ray crystallography was used to determine the structures of the crystalline phases.
- Phase transition temperatures were identified and correlated with structural changes.
Main Results:
- Three crystalline phases of XeF6 were identified, based on tetrameric XeF5+ and F- ions in eight-membered rings.
- Phase I (monoclinic) transforms to Phase II (orthorhombic) at ~10°C, requiring tetramer reorientation.
- Phase II transforms to Phase III (monoclinic) at ~-25°C, involving ordering of configurations.
Conclusions:
- The crystalline structure of XeF6 is highly sensitive to temperature.
- Phase transitions involve distinct molecular rearrangements and ordering phenomena.
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