Formula NiI2 | Density 5.38 g/cm³ | |
 | ||
Appearance iron-black solid (anhydrous); bluish-green solid (hexahydrate) | ||
Nickel(II) iodide is an inorganic compound with the formula NiI2. This paramagnetic black solid dissolves readily in water to give blue-green solutions of the aquo complexes. This blue-green colour is typical of hydrated nickel(II) 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(II) 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.
NiI2 has found 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(II) iodide.