Neptunium tetrachloride

Neptunium tetrachloride is a binary inorganic compound of neptunium metal and chlorine with the chemical formula NpCl₄.^[1][2]

Neptunium tetrachloride

Identifiers
CAS Number	15597-84-9 Y
3D model (JSmol)	Interactive image
InChI InChI=1S/4ClH.Np/h4*1H;/q;;;;+4/p-4 Key: XFAAJSLPXNXKKA-UHFFFAOYSA-J
SMILES [Np+4].[Cl-].[Cl-].[Cl-].[Cl-]
Properties
Chemical formula	Cl4Np
Molar mass	379 g·mol−1
Appearance	orange-brown crystals
Density	4.95 g/cm3
Melting point	538 °C (1,000 °F; 811 K)
Related compounds
Related compounds	Uranium tetrachloride, Thorium tetrachloride
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Synthesis

The compound can be prepared by:

• the reaction of neptunium nitride with HCl:^[3]

2 NpN + 8 HCl → N₂ + 4 H₂ + 2 NpCl₄

• the reaction of neptunium sesquisulfide with HCl:

Np₂S₃ + 8 HCl → 2 NpCl₄ + 3 H₂S + H₂

• the reaction of carbon tetrachloride with neptunium(IV) oxide or NpO₂. Neptunium tetrachloride is formed as a yellow sublimate.^[4]

NpO₂ + CCl₄ → NpCl₄ + CO₂

Other reactions are also used.^[5]

Physical properties

NpCl₄ crystallizes in tetragonal crystal system of space group I4/amd.^[6]

Chemical properties

The compound reacts with ammonia to produce neptunium trichloride:^[3]

6 NpCl₄ + 2 NH₃ → 6 NpCl₃ + 6 HCl + N₂

Neptunium tetrachloride can be reduced to neptunium trichloride by hydrogen at 450 °C.

2 NpCl₄ + H₂ → 2 NpCl₃ + 2HCl

NpCl₄ can form Lewis base adducts with non-protic solvents such as 1,2-dimethoxyethane (DME), pyridine and acetonitrile. These compounds are more accessible in practice than the binary NpCl₄ salt. Solvates of the general formula NpCl₄L_x may thus be isolated.^[7] The most commonly used starting material for metal-organic neptunium chemistry is NpCl₄(DME)₂, which can be isolated as a pink powder.^[8]

NpCl₄(DME)₂ in 1,2-dimethoxyethane.