Neptunium(V) fluoride

Neptunium(V) fluoride or neptunium pentafluoride is a chemical compound of neptunium and fluorine with the formula NpF₅.

Neptunium(V) fluoride

Names
IUPAC name Neptunium(V) fluoride
Other names Neptunium pentafluoride
Identifiers
CAS Number	31479-18-2
3D model (JSmol)	Interactive image
PubChem CID	165359232
CompTox Dashboard (EPA)	DTXSID701312633
InChI InChI=1S/5FH.Np/h5*1H;/q;;;;;+5/p-5 Key: QROYIGAVOZBRHJ-UHFFFAOYSA-I
SMILES F[Np](F)(F)(F)F
Properties
Chemical formula	NpF5
Molar mass	332 g/mol
Appearance	Bluish-white solid[1]
Melting point	318 °C[1] (dec.)
Structure
Crystal structure	Tetragonal, tI12[1]
Space group	I4/m, No. 87[2]
Lattice constant	a = 0.65358 nm, c = 0.44562 nm
Lattice volume (V)	0.1904 nm3
Formula units (Z)	2
Thermochemistry
Heat capacity (C)	133 ± 8 J/mol·K[1]
Std molar entropy (S⦵298)	200 ± 15 J/mol·K[1]
Std enthalpy of formation (ΔfH⦵298)	−1941 ± 25 kJ/mol[1]
Gibbs free energy (ΔfG⦵)	−1834 ± 25 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

Synthesis

Neptunium(V) fluoride can be prepared by reacting neptunium(VI) fluoride with iodine:^[1]

10 NpF₆ + I₂ → 10 NpF₅ + 2 IF₅

From the equation above, iodine pentafluoride is a byproduct.

Properties

Neptunium(V) fluoride thermally decomposes at 318 °C to produce neptunium(IV) fluoride and neptunium(VI) fluoride. Contrary to uranium(V) fluoride, neptunium(V) fluoride does not react with boron trichloride, but it reacts with lithium fluoride in anhydrous HF to produce LiNpF₆.^[1]