Please, provide any possible synthesis of Nb(OH)5. This compound does not exist in the nature. All the oxide-based substances of Nb(V) have polymeric forms like (Nb2O5)x(H2Oy) and are labelled as niobic acids
Haha! The description you've given seems strange. HF provokes reduction reactions. Hence, niobia'll change its structure to lower values of valences. Show me the reference where your version is accurately reported :)