Question

How do you name [Co(en)2CO3]Br?

Answer 1

Answer:

$[Co(en)_2CO_3]Br$

this is a carbonatobis(ethylenediamine)cobalt(III) bromide isomer (either  

Δ or  Λ ), because...

en , ethylenediamine, is a neutral ligand. The complex name warrants a new kind of prefix, bis, to indicate that there are two of them. If there were three, one would use tris.

$CO_3^2-$

is the carbonato ligand.

Br −  in the outer coordination sphere implies that the inner coordination sphere is a  +1 charge overall.

Thus, the oxidation state of cobalt is  + III