Rhenium (VI) oxide
Crystal structure | ||||||||||||||||
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__ Re 6+ __ O 2− | ||||||||||||||||
Crystal system |
cubic |
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Space group |
Pm 3 m (No. 221) |
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Lattice parameters |
a = 374.8 pm |
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General | ||||||||||||||||
Surname | Rhenium (VI) oxide | |||||||||||||||
other names |
Rhenium trioxide |
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Ratio formula | ReO 3 | |||||||||||||||
Brief description |
red to purple solid |
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External identifiers / databases | ||||||||||||||||
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properties | ||||||||||||||||
Molar mass | 234.21 g mol −1 | |||||||||||||||
Physical state |
firmly |
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density |
6.9 g cm −3 |
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Melting point |
400 ° C (decomposition) |
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solubility |
almost insoluble in water |
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safety instructions | ||||||||||||||||
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Thermodynamic properties | ||||||||||||||||
ΔH f 0 |
−605 kJ mol −1 |
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As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions . |
Rhenium (VI) oxide ReO 3 is a chemical compound and is one of the oxides of rhenium . It is a red crystalline solid. Rhenium (VI) oxide is known primarily for its crystal structure , which is used as a structure type. Rhenium (VI) oxide is the only stable oxide of the manganese group in the + VI oxidation state .
Extraction and presentation
Rhenium (VI) oxide can be obtained from rhenium (VII) oxide by reduction . The reaction is possible, for example, with carbon monoxide at about 200 ° C or elemental rhenium at 400 ° C.
Rhenium (VI) oxide can be obtained by reacting rhenium (VII) oxide with dioxane and water with slight heating. The intermediate dioxane complex is decomposed at 145 ° C, whereby the complex initially melts at around 100 ° C to a colorless to blue-green liquid, which after a short time decomposes to red rhenium (VI) oxide and volatile rhenium-free products.
properties
Physical Properties
Rhenium (VI) oxide is a moisture-sensitive red, purple-red to purple odorless solid, with a green sheen in transmitted light.
Rhenium (VI) oxide has a characteristic crystal structure that is similar to the perovskite structure. It differs from this only in the lack of a central atom (in perovskite calcium ). Each rhenium atom is surrounded by oxygen atoms in an octahedral manner , while the oxygen atoms are located between two rhenium atoms. It is thus a cubic primitive unit cell with the space group Pm 3 m (space group no. 221) and the lattice parameter a = 374.8 pm.
Rhenium (VI) oxide has some metallic properties, so the specific resistance is very low and decreases with falling temperatures. Rhenium (VI) oxide also has a metallic sheen.
Chemical properties
Rhenium (VI) oxide is not soluble in water or in dilute acids and bases . When boiled in hot lye, it disproportionates into ReO 2 and ReO 4 - .
It reacts with oxygen at elevated temperatures to form rhenium (VII) oxide. In concentrated nitric acid , reaction takes place to form perrhenic acid . It disproportionates in a vacuum at temperatures above 300 ° C to form rhenium (IV) oxide and rhenium (VII) oxide.
Individual evidence
- ↑ a b T.-S. Chang, P. Trucano: Lattice parameters and thermal expansion of ReO 3 between 291 and 464 K . In: Journal of Applied Crystallography . tape 11 , 1978, p. 286-288 , doi : 10.1107 / S0021889878013333 .
- ↑ a b c d e f data sheet Rhenium (VI) oxide, 99.9% (metals basis) from AlfaAesar, accessed on December 7, 2019 ( PDF )(JavaScript required) .
- ^ William M. Haynes: CRC Handbook of Chemistry and Physics . CRC Press, 2016, ISBN 978-1-4987-5429-3 , pp. 98 ( limited preview in Google Book search).
- ^ AF Holleman , N. Wiberg : Inorganische Chemie . 103rd edition. Volume 2: Subgroup elements, lanthanoids, actinides, transactinides. Walter de Gruyter, Berlin / Boston 2016, ISBN 978-3-11-049590-4 , p. 1921 (Reading sample: Part C - Subgroup elements. Google book search ).
- ↑ a b c Georg Brauer (Ed.) U. a .: Handbook of Preparative Inorganic Chemistry. 3rd, revised edition. Volume III, Ferdinand Enke, Stuttgart 1981, ISBN 3-432-87823-0 , p. 1616.
- ^ Dale L. Perry: Handbook of Inorganic Compounds, Second Edition . Taylor & Francis US, 2011, ISBN 1-4398-1462-7 , pp. 345 ( limited preview in Google Book search).
literature
- AF Holleman , E. Wiberg , N. Wiberg : Textbook of Inorganic Chemistry . 102nd edition. Walter de Gruyter, Berlin 2007, ISBN 978-3-11-017770-1 .
- NN Greenwood, A. Earnshaw: Chemistry of the Elements . 1st edition. VCH Verlagsgesellschaft, 1988, ISBN 3-527-26169-9