Ferric iodide, FeI3, has not as yet been prepared, but the possibility of its existence is perhaps indicated by the fact that hydrated ferric oxide dissolves in hydriodic acid, yielding a brown solution.
Two ferrous per-iodates are described by Kimmins, namely Fe5(IO6)2 and FeH3(IO6). The former is a brick-red crystalline salt produced on adding ferrous sulphate to a solution of K4I2O9.FeH3(IO6) results as a light brown powder on adding a solution of Na2H3IO6 to ferrous sulphate.
Two ferric per-iodates have been prepared, namely FeHI2O9 and Fe(IO4)3. The former is obtained by drying at 100° C. the light brown precipitate resulting from the interaction of solutions of ferric chloride and Na2H3IO6. It is also formed when K4I2O9 is used instead of the sodium salt. It is a reddish-brown powder, stable towards boiling dilute nitric acid. With concentrated nitric acid, however, Fe(IO4)3 is formed as a bright yellow powder. |