DecatantalateThe Last Member of the Group 5 Decametalate Family

A tetra-n-butylammonium (TBA) salt of [Ta10O28]6– was synthesized by heating
TBA6[H2Ta6O19] in toluene
for a prolonged period. X-ray structural analysis of TBA6[Ta10O28]·6H2O revealed that
the anion has the decametalate structure and is isostructural with
the decavanadate and decaniobate anions [a = 15.8517(8)
Å, b = 19.364(1) Å, c =
21.935(1) Å, β = 93.638(1)°, V =
6719.4(6) Å3, Z = 2, and space group P21/n at 292(2) K].