Neptunium(IV) fluoride

Neptunium(IV) fluoride or neptunium tetrafluoride is an inorganic compound with the formula NpF₄. It is a green salt and is isostructural with UF₄.^[3]

Neptunium(IV) fluoride

Names
IUPAC name Neptunium(IV) fluoride
Other names Neptunium tetrafluoride
Identifiers
CAS Number	14529-88-5
3D model (JSmol)	Interactive image
PubChem CID	165358598
CompTox Dashboard (EPA)	DTXSID901300818
InChI InChI=1S/4FH.Np/h4*1H;/q;;;;+4/p-4 Key: SOLQLNAXKAQIPH-UHFFFAOYSA-J
SMILES F[Np](F)(F)F
Properties
Chemical formula	NpF4
Molar mass	313 g/mol
Appearance	Green solid[1]
Structure
Crystal structure	Monoclinic, mS60[1]
Space group	C2/c, No. 15[2]
Lattice constant	a = 1.27 nm, b = 1.0082 nm, c = 0.833 nm α = 90°, β = 126.03°, γ = 90°
Lattice volume (V)	0.86256 nm3
Formula units (Z)	12
Thermochemistry
Heat capacity (C)	116 ± 4 J/mol·K[1]
Std molar entropy (S⦵298)	148 ± 3 J/mol·K[1]
Std enthalpy of formation (ΔfH⦵298)	−1874 ± 16 kJ/mol[1]
Gibbs free energy (ΔfG⦵)	−1783 ± 16 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

Alternative view of the structure of solid NpF₄.

Neptunium(IV) fluoride can be prepared by reacting neptunium(III) fluoride or neptunium dioxide with a gas mixture of oxygen and hydrogen fluoride at 500 °C:^[1]

4 NpF₃ + O₂ + 4 HF → 4 NpF₄ + 2 H₂O

It can also be prepared by treating neptunium dioxide with HF gas:^[1]

NpO₂ + 4 HF → NpF₄ + 2 H₂O