Indium complexes fluorides

At least for the chloride, a switch analogous to that postulated for the Cd2+ halide systems is clearly indicated, viz. from the octahedral arrangement presumed to exist in the hydrated indium (III) ion (75) to a tetrahedral halide complex. For the fluoride this interpretation might be too bold, considering the small size of the effect. 

The indium iodide complex [1-3] is > 99% extracted into diethyl ether from 0.5-2.5 M HI (6-30%). Gallium is not extracted under these conditions, but it is extracted from 6 M HCl. The hydriodic acid can be replaced by 0.5-3 M H2SO4 containing 15-20% of Kl. Chloride, bromide, fluoride, phosphate, and citrate do not interfere in the extraction of In from iodide media. Under the optimum conditions for the extraction, Tl, Cd, and Sn (and some Bi, Zn, Hg, and Sb) are extracted. Aluminium and Fe(II), like Ga, are not extracted. The indium iodide complex has also been extracted into chloroform containing N-benzylaniline [4,5]. 

Almost all the elements of the ammonium sulfide group give colored lakes with polyhydroxyanthraquinones and interfere with the direct test for indium. In a few cases the test may be carried out nevertheless. In the presence of aluminum, the interfering ion may be masked by formation of the complex [AlFg]- ion. A drop of the test solution is mixed with 3 or 4 drops of a saturated solution of sodium fluoride in a micro crucible. The test, as described, is then carried out using a drop of this mixture. 

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