structure. Therefore the two structures are non-superimposable. These two structures are isomers.
Coordination Sphere Isomers
Coordination isomers are two or more coordination compounds in which the composition within the coordination sphere (i.e., the metal atom plus the ligands that are bonded to it) is different (i.e., the connectivity between atoms is different).
Not all coordination compounds have coordination isomers.
Coordination sphere isomers have different physical and chemical properties.
Hydration Coordination Sphere Isomer
Aqua groups within the coordination sphere are bonded to the Cr atom by the oxygen atoms. The water of hydration with the complex cis-[Cr(OH2)4Cl2]∙H2O is not shown in the structure above.
For this structure only one chlorine atom remains inside the coordination sphere and bonded to the Cr atom. The water of hydration has moved inside the coordination sphere and replaced the chloro group. The displaced chloro group is now a counter ion not shown in the above structure.
Ionization Coordination Sphere Isomer
The sulfate group inside the coordination sphere is bonded to the Cr atom by an O atom. The bromide counter ion needed to maintain charge neutrality for the compound with the complex ion [Cr(NH3)5(OSO3)]+ is not shown in the above structure.
The bromine ion is bonded to the Cr atom at the bottom of the octahedral structure and has inside the coordination sphere displacing the sulfato group. The resulting sulfate counter ion is not shown in the above structure.
Coordination Coordination Sphere Isomer
The ammine groups are bonded to the Pt ion by
cis-[Pt(NH3)4Cl2] cis- [Pt(NH3)2Cl2]
For this structure two chloro ligands originally