Gadolinium perrhenate is an inorganic compound, with the chemical formula of Gd(ReO4)3. Its chemical formula is Gd(ReO₄)₃, representing gadolinium(III) perrhenate in its anhydrous form. It can be obtained by dissolving an excess of gadolinium oxide in a perrhenic acid solution (240 g/L) in the presence of hydrogen peroxide, from which the hydrates are precipitated.
Its tetrahydrate loses water by heating to obtain the anhydrous form, which then decomposes at high temperatures to generate gadolinium oxide and rhenium heptoxide. It also exists as hydrates, such as the tetrahydrate Gd(ReO₄)₃·4H₂O.
Properties
- Chemical formula: Gd(ReO4)3
- Solubility: soluble in water and ethanol
Preparation
The compound is synthesized by dissolving an excess of gadolinium oxide (Gd₂O₃) in a concentrated perrhenic acid (HReO₄) solution, typically at 240 g/L, in the presence of hydrogen peroxide (H₂O₂). This reaction precipitates the hydrated forms. The tetrahydrate can then be dehydrated by heating to yield the anhydrous compound.
Thermodynamic Properties
Studies on aqueous solutions of gadolinium perrhenate have focused on its behavior under extreme conditions due to the non-complexing nature of perrhenate ions, making it useful for isolating properties of Gd³⁺(aq). Key data include:
- Heat of solution of solid cubic Gd₂O₃ in dilute perrhenic acid (10⁻⁴ m) measured up to 596.30 K.
- Standard state thermodynamic properties of aqueous Gd(ReO₄)₃ determined up to 623.15 K.
- Standard partial molal heat capacities for aqueous gadolinium perrhenate derived from high-dilution calorimetry.
- Related data on Gd³⁺(aq) hydrolysis were obtained separately.
- These measurements were conducted using a high-temperature, high-pressure calorimeter at saturated vapor pressures.
Applications and Uses
No commercial or industrial applications are documented for gadolinium perrhenate. It appears primarily in scientific research, particularly for thermodynamic studies of aqueous rare-earth ions under high-temperature and high-pressure conditions, where perrhenate serves as a non-coordinating anion to avoid complex formation. Gadolinium compounds in general are used in magnetic resonance imaging (MRI) contrast agents, phosphors, and neutron absorbers, but perrhenate variants are not noted for these purposes.
Safety and Handling
As a compound containing gadolinium and rhenium, it should be handled with care due to potential toxicity. Gadolinium can accumulate in the body and cause nephrogenic systemic fibrosis in individuals with kidney issues, while rhenium compounds may be irritants. No specific toxicity data for this compound is available, but standard precautions for heavy metal salts apply.
