Rhenium trioxide

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Rhenium trioxide
Rhenium-trioxide-unit-cell-3D-balls-B.png REO3.JPG
Identifiers
CAS number 1314-28-9 YesY
PubChem 102110
EC number 215-228-8
Jmol-3D images Image 1
Properties
Molecular formula ReO3
Molar mass 234.205 g/mol
Appearance Deep red crystals
Density 6.92 g/cm3
Melting point 400 °C (decomposes)
Refractive index (nD) 1.68
Structure
Crystal structure Cubic, cP4
Space group Pm3m, SpaceGroup = 221
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
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Infobox references
Rhenium-trioxide-3D-vdW.png
ReO3 polyhedra

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[edit]

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[edit]

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[edit]

  1. ^ H. Nechamkin, C. F. Hiskey, "Rhenium(VI): Oxide (Rhenium Trioxide)" Inorganic Syntheses, 1950 Volume 3, pp. 186-188. doi:10.1002/9780470132340.ch49
  2. ^ a b 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. ^ a b Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. ISBN 0080379419. , p. 1047.