Dear Juliet,

Highly charged vanadate(V) cations >3+ rarely exist as the simple 'hydrated' tetra or hexa–aqua ion. The theoretical polarising power of the 'central metal ion' is so strong that they form oxocations  or oxyanions e.g.

For more on this topic, please use the following link:

http://www.docbrown.info/page07/transition03V.htm

Hoping this will be helpful,

Rafik

Thank you so much Rafik sir