Reddish-violet Salts, [Mo(OH)₄(CN)₄]K₄

Reddish-violet Salts is the potassium salt, [Mo(OH)₄(CN)₄]K₄.6H₂O, described above as MoO₂.4KCN.10H₂O, yields reddish-violet monoclinic tables:

a:b:c = 0.7324:1:0.5723.

The difference in water content, shown in the latter formula, is due to insufficient drying; if dried over sulphuric acid the salt has the composition [MoO₂(CN)₄]K₄.6H₂O.

The sodium salt, [Mo(OH)₄(CN)₄].12H₂O, is similar to the potassium salt, and yields [MoO₂(CN)₄]Na₄.6H₂O when dried over sulphuric acid.