# How do I find the oxidation number of a coordination complex

I actually know how to calculate the oxidation number for coordination complexes but some complexes like the below are giving some reistance

$\ce{[Cu(NH3)_2][Fe(H2O)_3]}$ (diamminecopper(?) triaquoferrate(?))

I just wrote this example now and don't know wether it exists or not I am rather concerned about how do I find their oxidation numbers