2. [Pt(NH3)5Cl]Br3
Answer: pentaamminechloroplatinum(IV) bromide
Solution: The complex ion is a cation, the counter anion is the 3 bromides.
The charge of the complex ion must be +3 since it bonds with 3 bromides.
The NH3 are neutral molecules while the chloride carries - 1 charge. Therefore, the oxidation number of platinum must be +4.