Uranium triiodide is an inorganic compound with the

chemical formula In chemistry, a chemical formula is a way of presenting information about the chemical proportions of atoms that constitute a particular chemical compound or molecule, using chemical element symbols, numbers, and sometimes also other symbol ...

UI₃. It is a black solid that is soluble in water.

Production

Uranium triiodide can be obtained from the direct reaction of its constituent elements: :2 U + 3 I₂ → 2 UI₃ When the reaction is conducted in

tetrahydrofuran Tetrahydrofuran (THF), or oxolane, is an organic compound with the formula (CH2)4O. The compound is classified as heterocyclic compound, specifically a cyclic ether. It is a colorless, water- miscible organic liquid with low viscosity. It is ...

(THF), the product is the blue complex UI₃(THF)₄.

Properties

It crystallizes in the

orthorhombic crystal system In crystallography, the orthorhombic crystal system is one of the 7 crystal systems. Orthorhombic lattices result from stretching a cubic lattice along two of its orthogonal pairs by two different factors, resulting in a rectangular prism with ...

( plutonium tribromide-type) in the

space group In mathematics, physics and chemistry, a space group is the symmetry group of an object in space, usually in three dimensions. The elements of a space group (its symmetry operations) are the rigid transformations of an object that leave it uncha ...

''Ccmm'' with the

lattice parameter A lattice constant or lattice parameter is one of the physical dimensions and angles that determine the geometry of the unit cells in a crystal lattice, and is proportional to the distance between atoms in the crystal. A simple cubic crystal has o ...

s ''a'' = 432.8 pm, ''b'' = 1401.1 pm, and ''c'' = 1000.5 pm and four

formula unit In chemistry, a formula unit is the empirical formula of any ionic or covalent network solid compound used as an independent entity for stoichiometric calculations. It is the lowest whole number ratio of ions represented in an ionic compound. E ...

s per

unit cell In geometry, biology, mineralogy and solid state physics, a unit cell is a repeating unit formed by the vectors spanning the points of a lattice. Despite its suggestive name, the unit cell (unlike a unit vector, for example) does not necessaril ...

. Uranium triiodide can be used as a Lewis acid catalyst for various Diels-Alder reactions carried out under mild conditions.

References

{{Actinide halides Uranium(III) compounds Iodides Actinide halides