Vanado-periodates

Vanadium pentoxide dissolves in boiling solutions of the alkali periodates to produce yellow or red, crystalline vanado-periodates, the compositions of which approximate to the following: 5Na₂O.5V₂O₅.2I₂O₇.xH₂O and 5K₂O.5V₂O₅.2I₂O₇.xH₂O. By altering the relative acidity of the solution, various other complexes have been obtained, e.g. 5Na₂O.7V₂O₅.I₂O₇.27H₂O; 6Na₂O.9V₂O₅.I₂O₇.48H₂O; 3Na₂O.2V₂O₅.I₂O₇.7H₂O; 3K₂O.2V₂O₅.I₂O₇.17½H₂O; and 3(NH₄)₂O.2V₂O₅.I₂O₇.6½H₂O. The water in the last three compounds has been shown not to be water of constitution, and the salts can be regarded as tribasic vanado-periodates of the general formula ; two oxygen atoms in the periodate ion [IO₆]^V have been replaced by (VO₃)' radicals.