Neptunium silicide

Neptunium silicide is a binary inorganic compound of neptunium and silicon with the chemical formula. The compound forms crystals and does not dissolve in water.

Synthesis
Heating neptunium trifluoride with powdered silicon in vacuum:
 * $$\mathsf{ 4 NpF_3 + 11Si \ \xrightarrow{1500^oC}\ 4NpSi_2 + 3SiF_4 }$$

Physical properties
Neptunium silicide forms crystals of tetragonal crystal system, space group I41/amd, cell parameters: a = 0.396 nm, c = 1.367 nm, Z = 4.

Neptunium disilicide does not dissolve in water.

Chemical properties
Neptunium disilicide reacts with HCl:
 * $$\mathsf{ NpSi_2 + 8HCl \ \xrightarrow\ NpCl_4 + 2SiH_4 }$$