Nickel(II) iodide

Nickel(II) iodide is an inorganic compound with the formula NiI₂. This paramagnetic black solid dissolves readily in water to give bluish-green solutions,^[1] from which crystallizes the aquo complex [Ni(H₂O)₆]I₂ (image above).^[2] This bluish-green colour is typical of hydrated nickel(II) compounds. Nickel iodides find some applications in homogeneous catalysis.

Nickel(II) iodide

Nickel(II) iodide hexahydrate, NiI2•6H2O Hexahydrate
Nickel(II) iodide
Names
IUPAC name Nickel(II) iodide
Other names Nickelous iodide
Identifiers
CAS Number	13462-90-3 Y
3D model (JSmol)	Interactive image hexahydrate: Interactive image
ChemSpider	24252 hexahydrate: 32816205
ECHA InfoCard	100.033.319
EC Number	236-666-6
PubChem CID	26038 hexahydrate: 138962054
UNII	AQ9OJ30HDD Y
CompTox Dashboard (EPA)	DTXSID1065479
InChI Key: BFSQJYRFLQUZKX-UHFFFAOYSA-L InChI=1S/2HI.Ni/h2*1H;/q;;+2/p-2 hexahydrate: InChI=1S/2HI.Ni.6H2O/h2*1H;;6*1H2/q;;+2;;;;;;/p-2 Key: IBSOYFJDSVROOT-UHFFFAOYSA-L
SMILES [Ni](I)I hexahydrate: I[Ni]I.O.O.O.O.O.O
Properties
Chemical formula	I2Ni
Molar mass	312.5023 g·mol−1
Appearance	iron-black solid (anhydrous) bluish-green solid (hexahydrate)
Density	5.384 g/cm3
Melting point	780 °C (1,440 °F; 1,050 K) (anhydrous) 43 °C (hexahydrate, loses water)
Solubility in water	124.2 g/100 mL (0 °C) 188.2 g/100 mL (100 °C)
Solubility	alcohols
Magnetic susceptibility (χ)	+3875.0·10−6 cm3/mol
Hazards
NFPA 704 (fire diamond)	2 0 0
Related compounds
Other anions	nickel(II) chloride, nickel(II) bromide, nickel(II) fluoride
Other cations	cobalt iodide, copper iodide,
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Y verify (what is YN ?) Infobox references

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.^[3]

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.^[4]

Applications

Catalysis

NiI₂ has some industrial applications as a catalyst in carbonylation reactions.^[5] It is also has niche uses as a reagent in organic synthesis, especially in conjunction with samarium(II) iodide.^[6]

Like many nickel complexes, those derived from hydrated nickel iodide have been used in cross coupling.^[7]

NiI₂ as the Ni(II) precatalyst in the aryl iodide and alkyl iodide cross coupling

Spintronics

At 60 K (−213.2 °C; −351.7 °F) 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.^[8]