Neptunium (III) bromide

Crystal structure
α-NpBr 3 (left) β-NpBr 3 (right)
__  Np 3+      __  __  Br -
Crystal system	α-NpBr 3 : hexagonal β-NpBr 3 : orthorhombic
Space group	α-NpBr 3 : P 6 3 / m (No. 176) β-NpBr 3 : Ccmm (No. 63, position 2)
Lattice parameters	α-NpBr 3 : a = 791.7 pm c = 438.2 pm β-NpBr 3 : a = 411 pm b = 1265 pm c = 915 pm
General
Surname	Neptunium (III) bromide
other names	Neptunium tribromide
Ratio formula	NpBr 3
Brief description	green solid
External identifiers / databases
CAS number 20730-39-6 Wikidata Q1977868
properties
Molar mass	476.76 g mol −1
Physical state	firmly
density	6.62 g cm −3
Hazard and safety information
Radioactive
GHS hazard labeling no classification available
Thermodynamic properties
ΔH f 0	−185 kcal mol −1
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Neptunium (III) bromide is a chemical compound made up of the elements neptunium and bromine . It has the formula NPBR ₃ and belongs to the class of the bromides .

presentation

Neptunium (III) bromide can be produced by reacting neptunium (IV) oxide  (NpO ₂ ) with aluminum bromide  (AlBr ₃ ).

${\displaystyle {\ce {6 NpO2 + 8 AlBr3 -> 6 NpBr3 + 4 Al2O3 + 3 Br2}}}$

properties

Physical Properties

Neptunium (III) bromide is a green solid. It crystallizes in two different forms:

• α-NpBr ₃ in the hexagonal crystal system in the space group  P 6 ₃ / m (No. 176) with the lattice parameters a  = 791.7  pm and c  = 438.2 pm. It is isostructural to uranium (III) chloride .
• β-NpBr ₃ in the orthorhombic crystal system ( plutonium (III) bromide type) in the space group  Ccmm (No. 63, position 2) with the lattice parameters a  = 411  pm , b  = 1265 pm and c  = 915 pm and four formula units per Unit cell . It is isostructural to the bromides of the actinide elements plutonium to californium .

The hexahydrate, which is also green, has a monoclinic crystal structure with the space group  P 2 / n (No. 13, position 2) .

Chemical properties

Heating neptunium (III) bromide with excess bromine at 425 ° C leads to neptunium (IV) bromide  (NpBr ₄ ).

${\displaystyle {\ce {2 NpBr3 + Br2 -> 2 NpBr4}}}$

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.

Individual evidence

1. ↑ ^{a b c d e f} C. Keller: The chemistry of Neptunium. In: Fortschr. chem. Forsch. , 1969/70 , 13/1 , p. 69.
2. ^ AF Holleman , E. Wiberg , N. Wiberg : Textbook of Inorganic Chemistry . 102nd edition. Walter de Gruyter, Berlin 2007, ISBN 978-3-11-017770-1 , p. 1969.
3. ↑ ^{a b c d e} Gmelin's Handbook of Inorganic Chemistry , System No. 71, Transurane, Part C, pp. 148-150.
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.
5. ↑ ^{a b} Georg Brauer (Ed.), With the collaboration of Marianne Baudler u a .: Handbook of Preparative Inorganic Chemistry. 3rd, revised edition. Volume II, Ferdinand Enke, Stuttgart 1978, ISBN 3-432-87813-3 , p. 1268.

literature

• Zenko Yoshida, Stephen G. Johnson, Takaumi Kimura, John R. Krsul: Neptunium , 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. 699-812 ( doi : 10.1007 / 1-4020-3598-5_6 ).
• C. Keller: The chemistry of neptunium. In: Fortschr. chem. Forsch. , 1969/70 , 13/1 , pp. 1–124 ( doi : 10.1007 / BFb0051170 ).