Question: cis-trans isomerism is exhibited by which one of these ions?
Answer: Octahedral complex ions* The octahedral tetraamminedichloridocobalt(III) ion, [Co(NH3)4Cl2]+ , shown below can exist as cis and trans isomers. The cis isomer has the chlorine atoms (green balls) adjacent to each other, and the trans isomer has them across from each other.