Complex Molybdoselenites

Complex Molybdoselenites, obtained by acidifying solutions containing alkali molybdate and selenite, have been described. The composition of the products depends upon the ratio of molybdate to selenious acid present in the solution; when the selenium dioxide is in excess, the ratio SeO₂:MoO₃ is very nearly 1:1, and the following salts have been prepared: -

2(NH₄)₂O.5SeO₂.5MoO₃.8H₂O, white microscopic prisms;

2K₂O.4SeO₂.4MoO₃.7H₂O, microscopic prisms;

BaO.2SeO₂.2MoO₃.7H₂O, white crystals.

When less than 1 molecule of selenium dioxide is present to 1 molecule of molybdate, salts containing 2SeO₂:5MoO₃ and 2SeO₂:8MoO₃, are obtained. Yellow uncrystallisable compounds containing 2SeO₂:12MoO₃ have also been described.