Nickel(II) iodide


Nickel iodide is an inorganic compound with the formula NiI2. This paramagnetic black solid dissolves readily in water to give bluish-green solutions, from which crystallizes the aquo complex I2. This bluish-green colour is typical of hydrated nickel compounds. Nickel iodides find some applications in homogeneous catalysis.

Structure and synthesis

The anhydrous material crystallizes in the CdCl2 motif, featuring octahedral coordination geometry at each Ni center. NiI2 is prepared by dehydration of the pentahydrate.
NiI2 readily hydrates, and the hydrated form can be prepared by dissolution of nickel oxide, hydroxide, or carbonate in hydroiodic acid. The anhydrous form can be produced by treating powdered nickel with iodine.

Applications

Catalysis

NiI2 has some industrial applications as a catalyst in carbonylation reactions. It is also has niche uses as a reagent in organic synthesis, especially in conjunction with samarium iodide.
Like many nickel complexes, those derived from hydrated nickel iodide have been used in cross coupling.

Spintronics

At crystalline NiI2 exhibits p-wave magnetism, in which the spins of nickel atoms became arranged in a spiral pattern in two orientations. The orientations can be switched via a small electrical current. If it can be applied in digital devices, this spintronics behavior requires far less current than the conventional charge-based electronics that powers devices such as computers and phones.