Sodium and Ammonium Decavanadates V

Submitted by GARRETT K. JOHNSON and R. KENT MURMANN Checked by R. DEAVINt and W. P. GRIFFITHt 

The aqueous chemistry of vanadium(V) is not very well understood. One reason for this may be the lack of well-defined compounds of known composition and structure. 

Recent studies of the 180 isotropic exchange of [V 0028]6 and the orthovanadate ion, [V04] 3 , have shown slow kinetic exchange (fy2 minutes to hours) and have proven the identity of discrete decavanadate ions in solution. 

At this time the decavanadate ion is better characterized than any other aqueous vanadium(V) species and may be the starting material for future structural advances in vanadium(V) chemistry. Presented here are simple 

Two general approaches to syntheses seem to exist. In one method, exemplified in Section A for the sodium salt, a solution of a simple vanadate is acidified in a controlled way to produce the condensed [V100M] 6 ion, which is then crystallized as the salt of the original cation. This method has somewhat limited applicability inasmuch as the solubilities of many simple vanadates (e.g., of calcium and ammonium) are too low. 

---