# Isomerism and namegiving

Is this the right chemical formula of the $$\ce{Rb[Pt(NH3)Br2Cl]}$$ complex: rubidium amminedibromidochloridoplatinate(II)?

And is it correct that it has geometric isomerism, being square planar with a cis- and trans-isomers, leaving the rubidium out?

Your formula, $$\ce{Rb[Pt(NH3)Br2Cl]}$$ is correct for the named complex, rubidium amminedibromochloroplatinate(II) (For clear understanding of naming, you may read Naming Coordination Compounds-1 and Naming Coordination Compounds-2).
Cis-trans-isomerism is one of the more common types. Cis-trans (geometric) isomers of coordination compounds differ from one another only in the manner, in which the ligands are distributed spatially. Most of platinum(II) complexes are square planner. Most common example is Cisplatin ($$\ce{Pt(NH3)2Cl2]}$$) where the each of two ammonia molecules and the two chlorine atoms are situated next to one another (see the diagram in the blue box below), and hence isomer is called the cis (Latin for “on this side”). Thus, coordination name for Cisplatin is cis-diamminedichloroplatinum(II) (Wikipedia).