Tetraiodonickelate is a complex ion of
nickel
Nickel is a chemical element with symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. Nickel is a hard and ductile transition metal. Pure nickel is chemically reactive but large pieces are slow to ...
with four
iodide atoms
4">iI4sup>2− arranged in a tetrahedron.
[ 4">iI4sup>2− is red in solution. This colour is due to absorption around 530 nm and below 450 nm. Maximum light transmission is around 620 nm, which is red. A broad weak absorption in the near infrared is at 740 nm.][ The magnetic moment is anomalously low.
A mixture of lithium iodide and nickel iodide in water or ]methanol
Methanol (also called methyl alcohol and wood spirit, amongst other names) is an organic chemical and the simplest aliphatic alcohol, with the formula C H3 O H (a methyl group linked to a hydroxyl group, often abbreviated as MeOH). It is a ...
can partition NiI42− ions into a cyclohexane
Cyclohexane is a cycloalkane with the molecular formula . Cyclohexane is non-polar. Cyclohexane is a colorless, flammable liquid with a distinctive detergent-like odor, reminiscent of cleaning products (in which it is sometimes used). Cyclohexan ...
-amine
In chemistry, amines (, ) are compounds and functional groups that contain a basic nitrogen atom with a lone pair. Amines are formally derivatives of ammonia (), wherein one or more hydrogen atoms have been replaced by a substituen ...
mixture. The solution formed is blood red.
History
Already in 1909 Cambi had noticed that a mixture of nickel 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, from which crystallizes the aquo complex i(H2O)62 (image above). This bluish-green colour ...
and sodium iodide
Sodium iodide (chemical formula NaI) is an ionic compound formed from the chemical reaction of sodium metal and iodine. Under standard conditions, it is a white, water-soluble solid comprising a 1:1 mix of sodium cations (Na+) and iodide anions (I ...
dissolved in acetone has a red colour. This red colour was due to the presence of tetraiodonickelate.
Salts
Bis-triphenylmethylarsonium tetraiodoronickelate 6H5)3CH3As">C6H5)3CH3Assub>2NiI4 is red in colour.[ It can be made from triphenylmethylarsonium iodide and nickel iodide in hot ethanol. The red flakes that precipitate must be filtered before the alcohol cools, else the compound decomposes.][
Bis(tetraethylammonium) tetraiodonickelate has a molecular weight of 826.8135 and a CAS number of 13927-28-1.]
1,2,6-trimethyl-pyrazinium-tetraiodonickelate has CAS 88227-96-7.
References
{{nickel compounds
Nickel complexes
Iodine compounds