THE EAN RULE SAYS....count the total electrons and subtract the no of electrons for +ve charge and add for negative charge...

1>no of electrons for central metal ion here = atomic no. Z=24

2>treat every ligand to be donating 2 electrons...that means for 6 ligands....6*2 =12 electrons

3>now u gotta subtract the +3 charge

4>so total electrons = 24+12-(+3) = 33, which doesnt match any inert gas configuration [the magic number configuration]. It possesses 2/8/18/5....so doesnt follow EAN rule for stability of complex!!!!