Rhenium trioxide
| |||
Names | |||
---|---|---|---|
IUPAC name
Rhenium trioxide | |||
Other names
Rhenia | |||
Identifiers | |||
1314-28-9 | |||
EC number | 215-228-8 | ||
| |||
Jmol-3D images | Image | ||
PubChem | 102110 | ||
| |||
Properties | |||
ReO3 | |||
Molar mass | 234.205 g/mol | ||
Appearance | Deep red crystals | ||
Density | 6.92 g/cm3 | ||
Melting point | 400 °C (752 °F; 673 K) (decomposes) | ||
Refractive index (nD) |
1.68 | ||
Structure | |||
Crystal structure | Cubic, cP4 | ||
Space group | Pm3m, SpaceGroup = 221 | ||
Except where noted otherwise, data is given for materials in their standard state (at 25 °C (77 °F), 100 kPa) | |||
verify (what is: / ?) | |||
Infobox references | |||
Rhenium trioxide or rhenium(VI) oxide is the inorganic compound with the formula ReO3. It is a red solid with a metallic lustre. It is the only stable trioxide of the Group 7 elements (Mn, Tc, Re).
Preparation, structure
Rhenium trioxide can be formed by reducing rhenium(VII) oxide with carbon monoxide. [1]
- Re2O7 + CO → 2 ReO3 + CO2
Re2O7 can also be reduced with dioxane.[2]
Rhenium oxide crystallizes with a primitive cubic unit cell, with a lattice parameter of 3.742 Å (374.2 pm). The structure of ReO3 is similar to that of perovskite (ABO3), without the large A cation at the centre of the unit cell. Each rhenium center is surrounded by an octahedron defined by six oxygen centers. These octahedra share corners to form the 3-dimensional structure. The coordination number of O is 2 because each oxygen atom has 2 neighbouring Re atoms.[3]
Properties
Upon heating to 400 °C, it undergoes disproportionation:[2]
- 6 ReO3 → Re2O7 + 4 ReO2
ReO3 is unusual for an oxide because it exhibits very low resistivity. It behaves like a metal in that its resistivity decreases as its temperature decreases. At 300 K, its resistivity is 100.0 nΩ·m, whereas at 100 K, this decreases to 6.0 nΩ·m, 17 times less than at 300 K.[3]
References
- ↑ H. Nechamkin, C. F. Hiskey, "Rhenium(VI): Oxide (Rhenium Trioxide)" Inorganic Syntheses, 1950 Volume 3, pp. 186-188. doi:10.1002/9780470132340.ch49
- ↑ 2.0 2.1 G. Glemser "Rhenium (VI) Oxide" Handbook of Preparative Inorganic Chemistry, 2nd Ed. Edited by G. Brauer, Academic Press, 1963, NY. Vol. 2. p. 1482.
- ↑ 3.0 3.1 Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. ISBN 0080379419., p. 1047.
|