Curium (III) fluoride

Crystal structure
	__ cm 3+ __ F -
Crystal system	hexagonal
Space group	P 6 3 / mmc (No. 194)
Lattice parameters	a = 699.9 pm ; c = 717.9 pm
Coordination numbers	Cm [9], F [3]
General
Surname	Curium (III) fluoride
other names	Curium trifluoride
Ratio formula	CmF 3
Brief description	colorless solid
External identifiers / databases
Wikidata	Q1144604
properties
Molar mass	depending on the isotope: 295–309 g · mol −1
Physical state	firmly
Melting point	1406 ° C
solubility	almost insoluble in water (10 mg l −1 )
Hazard and safety information
	; Radioactive
GHS hazard labeling ; no classification available
GHS hazard labeling ; no classification available
	As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Curium (III) fluoride is a chemical compound made up of the elements curium and fluorine . It has the formula CmF ₃ and belongs to the fluoride class of substances . Since all isotopes of curium are only artificially produced, it has no natural occurrence.

presentation

Curium (III) fluoride can be produced by reacting an aqueous curium solution with fluoride salts in a weakly acidic environment .

{\ displaystyle {\ ce {Cm ^ 3 + (aq) + 3 F ^ - (aq) -> CmF3 (s) v}}}

A second possibility is the reaction of curium (III) hydroxide with hydrofluoric acid . Curium (III) fluoride produced in this way always contains a few molecules of crystal water . The anhydrous salt can be obtained by drying with hot gaseous hydrogen fluoride or by drying in a desiccator over phosphorus (V) oxide .

properties

Curium (III) fluoride is a colorless solid that melts at 1406 ° C. The molar mass depends on the isotope used or the isotope composition. It crystallizes in the lanthanum fluoride structure with the lattice parameters a = 699.9 pm and c = 717.9 pm. Each curium nucleus is surrounded by nine fluorine nuclei in a distorted triple-capped trigonal-prismatic structure. The standard entropy of formation Δ _fH ⁰ is estimated to be 1660 kJ / mol, the entropy of formation Δ _fS ⁰ to 121 J mol ⁻¹ K ⁻¹ (298 K).

use

Metallic curium can be obtained from curium (III) fluoride by reduction . For this purpose, this is caused to react with elemental barium in reaction apparatuses made of tantalum and tungsten in an environment free of water and oxygen .

{\ displaystyle {\ ce {2 CmF3 + 3 Ba -> 2 Cm + 3 BaF2}}}

safety instructions

Classifications according to the CLP regulation are not available because they only include chemical hazard and play a completely subordinate role compared to the hazards based on radioactivity . The latter also only applies if the amount of substance involved is relevant.

literature

Gregg J. Lumetta, Major C. Thompson, Robert A. Penneman, P. Gary Eller: Curium , in: Lester R. Morss, Norman M. Edelstein, Jean Fuger (Eds.): The Chemistry of the Actinide and Transactinide Elements , Springer, Dordrecht 2006; ISBN 1-4020-3555-1 , pp. 1397-1443 ( doi : 10.1007 / 1-4020-3598-5_9 ).

Individual evidence

Jump up ↑ LB Asprey, TK Keenan, FH Kruse: Crystal Structures of the Trifluorides, Trichlorides, Tribromides, and Triiodides of Americium and Curium , in: Inorg. Chem. , 1965 , 4 (7), pp. 985-986 ( doi: 10.1021 / ic50029a013 ).
^ ^A ^b ^c Gregg J. Lumetta, Major C. Thompson, Robert A. Penneman, P. Gary Eller: Curium , in: Lester R. Morss, Norman M. Edelstein, Jean Fuger (Eds.): The Chemistry of the Actinide and Transactinide Elements , Springer, Dordrecht 2006; ISBN 1-4020-3555-1 , pp. 1397-1443 ( doi : 10.1007 / 1-4020-3598-5_9 ).
↑ ^a ^b B. B. Cunningham: "Compounds of the Actinides", Preparative and Inorganic Reactions , Vol. 3, New York 1966, pp. 79-121.
↑ The hazards emanating from radioactivity do not belong to the properties to be classified according to the GHS labeling. With regard to other hazards, this substance has either not yet been classified or a reliable and citable source has not yet been found.
↑ Gmelin's Handbook of Inorganic Chemistry , System No. 71, Transurane, Part C, p. 102.
^ RA Penneman, RR Ryan, A. Rosenzweig: Structural systematics in actinide fluoride complexes , in: Structure & Bonding , 1973 , 13 , pp. 1-52. doi : 10.1007 / 3-540-06125-8_1 .
↑ JL Burnett: Melting points of CmF ₃ and AmF ₃ , in: J. Inorg. Nucl. Chem. , 1966 , 28 (10), pp. 2454-2456 ( doi: 10.1016 / 0022-1902 (66) 80158-6 ).
^ JC Wallmann, WWT Crane, BB Cunningham: The Preparation and Some Properties of Curium Metal , in: J. Am. Chem. Soc. , 1951 , 73 (1), pp. 493-494 ( doi: 10.1021 / ja01145a537 ).

[1] Jump up ↑ LB Asprey, TK Keenan, FH Kruse: Crystal Structures of the Trifluorides, Trichlorides, Tribromides, and Triiodides of Americium and Curium , in: Inorg. Chem. , 1965 , 4 (7), pp. 985-986 ( doi: 10.1021 / ic50029a013 ).

[Morrs-2] A ^b ^c Gregg J. Lumetta, Major C. Thompson, Robert A. Penneman, P. Gary Eller: Curium , in: Lester R. Morss, Norman M. Edelstein, Jean Fuger (Eds.): The Chemistry of the Actinide and Transactinide Elements , Springer, Dordrecht 2006; ISBN 1-4020-3555-1 , pp. 1397-1443 ( doi : 10.1007 / 1-4020-3598-5_9 ).

[cunn-3] B. B. Cunningham: "Compounds of the Actinides", Preparative and Inorganic Reactions , Vol. 3, New York 1966, pp. 79-121.

[NV-4] The hazards emanating from radioactivity do not belong to the properties to be classified according to the GHS labeling. With regard to other hazards, this substance has either not yet been classified or a reliable and citable source has not yet been found.

[Gmelin-5] Gmelin's Handbook of Inorganic Chemistry , System No. 71, Transurane, Part C, p. 102.

[6] RA Penneman, RR Ryan, A. Rosenzweig: Structural systematics in actinide fluoride complexes , in: Structure & Bonding , 1973 , 13 , pp. 1-52. doi : 10.1007 / 3-540-06125-8_1 .

[7] JL Burnett: Melting points of CmF ₃ and AmF ₃ , in: J. Inorg. Nucl. Chem. , 1966 , 28 (10), pp. 2454-2456 ( doi: 10.1016 / 0022-1902 (66) 80158-6 ).

[CM_METALL-8] JC Wallmann, WWT Crane, BB Cunningham: The Preparation and Some Properties of Curium Metal , in: J. Am. Chem. Soc. , 1951 , 73 (1), pp. 493-494 ( doi: 10.1021 / ja01145a537 ).