S. Himeno et al., RAMAN STUDIES ON THE IDENTIFICATION OF ISOPOLYMOLYBDATES IN AQUEOUS-SOLUTION, Bulletin of the Chemical Society of Japan, 70(3), 1997, pp. 631-637
Molybdenum(VI) solutions were investigated in detail by Raman spectros
copy with a view to establishing the speciation of the predominant pol
ynuclear species (isopolymolybdates) formed in aqueous solution. The m
ost intense Raman frequencies due to asymmetric stretching vibration o
f Mo=O were very sensitive to even small changes of the structure of t
he isopolymolybdates. As the pH was lowered, the major Raman line show
ed no gradual shift but exhibited a discrete change. Evidence was obta
ined for the existence of Mo7O246- (pH 4-6), Mo3O102- (pH 3.5-5), alph
a-Mo8O264-(pH 2-5). beta-Mo8O264- (pH 1.5-4), and Mo36O1128- (pH 0.5-1
.5). On the other hand, neither of Mo6O192- and gamma-Mo8O264- existed
in any appreciable amount in aqueous solution.