Tetraiodonickelate(II)
Inorganic dianion
From Wikipedia, the free encyclopedia
Tetraiodonickelate(II) is a complex dianion of nickel with four iodide ions arranged in a tetrahedral structure.[1] [NiI4]2− is red in solution.[1] This colour is due to absorption around 530 nm and below 450 nm.[1] Maximum light transmission is around 620 nm, which is red.[1] A broad weak absorption in the near infrared is at 740 nm.[1] The magnetic moment is anomalously low.[2]
A mixture of lithium iodide and nickel iodide in water or methanol can partition [NiI4]2− ions into a cyclohexane-amine mixture. The solution formed is blood red.[3]
History
In 1909, Cambi[clarification needed] had noticed that a mixture of nickel iodide and sodium iodide dissolved in acetone has a red colour. This red colour was due to the presence of tetraiodonickelate.[1]
Salts
Bis(triphenylmethylarsonium) tetraiodonickelate is red in colour and has the chemical formula [(C6H5)3CH3As]2[NiI4].[1][4] It can be made from triphenylmethylarsonium iodide and nickel iodide in hot ethanol. The red flakes that precipitate must be filtered before the ethanol cools, otherwise the compound begins to decompose.[1]
Bis(tetraethylammonium) tetraiodonickelate has a molecular weight of 826.8135 and a CAS number of 13927-28-1.[5] It has the chemical formula [(C2H5)4N]2[NiI4].