Curium(III) fluoride

Curium(III) fluoride or curium trifluoride is the chemical compound composed of curium and fluorine with the formula CmF₃.^[3] It is a white, nearly insoluble salt that has the same crystal structure as LaF₃. It precipitates as a hydrate when fluoride ions are added to a weakly acidic Cm(III) solution; alternatively it can be synthesized by reacting hydrofluoric acid with Cm(OH)₃. The anhydrous form is then obtained by desiccation or by treatment with hydrogen fluoride gas.^[1]

Curium(III) fluoride

Crystal structure
Names
IUPAC name Curium(III) fluoride
Other names Curium trifluoride
Identifiers
CAS Number	13708-79-7
3D model (JSmol)	Interactive image
ChemSpider	57569004 Y
PubChem CID	101943145
InChI InChI=1S/Cm.3FH/h;3*1H/q+3;;;/p-3 Y
SMILES F[Cm](F)F
Properties
Chemical formula	CmF3
Appearance	Colorless solid[1]
Melting point	1406 ± 20 °C;[1]
Solubility in water	~10 mg/L
Structure
Crystal structure	Rhombohedral, hR24
Space group	P3c1, No. 165[2]
Lattice constant	a = 0.7012 nm, c = 0.7198 nm
Lattice volume (V)	0.30650
Formula units (Z)	6
Thermochemistry
Std molar entropy (S⦵298)	121 J/mol·K[1]
Std enthalpy of formation (ΔfH⦵298)	−1660 kJ/mol[1]
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Preparation

Curium fluoride can be prepared by in the reaction of curium with fluorine ions in an aqueous solution under weakly acidic conditions:

Cm³⁺ (aq) + 3 F⁻ (aq) → CmF₃ (s) ↓

Another possible preparation is the reaction of curium hydroxide with hydrofluoric acid, which also produces a hydrate of Curium fluoride.^[4]