β-NpBr3: orthorhombic β-NpBr3: Ccmm (No.

63) Neptunium(III) bromide is a bromide of neptunium, with the chemical formula of NpBr3.

Neptunium(III) bromide can be prepared by reacting neptunium dioxide and aluminium bromide:[3] Neptunium(III) bromide is a green solid.

It can crystallize in two crystal systems: Neptunium(III) bromide also has a green hexahydrate, which is monoclinic.

[3] At 425 °C, neptunium(III) bromide bromide can be further brominated by bromine to form neptunium(IV) bromide.