Tetraiodonickelate(II) is a complex ion of nickel with four iodide ions [NiI4]2− arranged in a tetrahedron.[1] [NiI4]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.[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]
Gill
was invoked but never defined (see the help page).