Zirconium(III) iodide is an
inorganic compound
An inorganic compound is typically a chemical compound that lacks carbon–hydrogen bondsthat is, a compound that is not an organic compound. The study of inorganic compounds is a subfield of chemistry known as ''inorganic chemistry''.
Inorgan ...
with the
formula
In science, a formula is a concise way of expressing information symbolically, as in a mathematical formula or a ''chemical formula''. The informal use of the term ''formula'' in science refers to the general construct of a relationship betwe ...
ZrI
3.
Preparation
Like other
group 4 Group 4 may refer to:
*Group 4 element
Group 4 is the second group of transition metals in the periodic table. It contains only the four elements titanium (Ti), zirconium (Zr), hafnium (Hf), and rutherfordium (Rf). The group is also called the t ...
trihalides, zirconium(III) iodide can be prepared from
zirconium(IV) iodide
Zirconium(IV) iodide is the chemical compound with the formula Zr I4. It is the most readily available iodide of zirconium. It is an orange-coloured solid that degrades in the presence of water. The compound was once prominent as an intermediate ...
by high-temperature reduction with
zirconium
Zirconium is a chemical element; it has Symbol (chemistry), symbol Zr and atomic number 40. First identified in 1789, isolated in impure form in 1824, and manufactured at scale by 1925, pure zirconium is a lustrous transition metal with a greyis ...
metal, although incomplete reaction and contamination of the product with excess metal often occurs.
:3 ZrI
4 + Zr → 4 ZrI
3
An alternative is to crystallise zirconium(III) iodide from a solution of zirconium(III) in
aluminium triiodide. The solution is prepared by reducing a
eutectic solution of ZrI
4 in liquid AlI
3 at a temperature of 280–300 °C with metallic zirconium or aluminium.
Structure and bonding
Zirconium(III) iodide has a
lower magnetic moment than
is expected for the d
1 metal ion Zr
3+, indicating non-negligible Zr–Zr bonding.
The
crystal structure
In crystallography, crystal structure is a description of ordered arrangement of atoms, ions, or molecules in a crystalline material. Ordered structures occur from intrinsic nature of constituent particles to form symmetric patterns that repeat ...
of zirconium(III) iodide is based on
hexagonal close packing
In geometry, close-packing of equal spheres is a dense arrangement of congruent spheres in an infinite, regular arrangement (or lattice). Carl Friedrich Gauss proved that the highest average density – that is, the greatest fraction of space occ ...
of
iodide
An iodide ion is I−. Compounds with iodine in formal oxidation state −1 are called iodides. In everyday life, iodide is most commonly encountered as a component of iodized salt, which many governments mandate. Worldwide, iodine deficiency ...
ions with one third of the
octahedral
In geometry, an octahedron (: octahedra or octahedrons) is any polyhedron with eight faces. One special case is the regular octahedron, a Platonic solid composed of eight equilateral triangles, four of which meet at each vertex. Many types of i ...
interstices occupied by Zr
3+ ions.
The structure consists of parallel chains of
face-sharing octahedra
with unequally spaced metal atoms. The Zr–Zr separation alternates between 3.17 Å and 3.51 Å.
ZrCl
3, ZrBr
3 and ZrI
3 adopt structures very similar to the
β-TiCl3 structure.
In all three ZrX
3 there is some elongation of the octahedra along the metal-metal axis, partly due to metal-metal repulsion,
but the elongation is most pronounced in
the chloride, moderate in
the bromide and negligible in the iodide.
References
{{DEFAULTSORT:Zirconium(Iii) Iodide
Zirconium(III) compounds
Iodides
Metal halides