Substitution Reactions
In solution, we can replace one ligand by another (aquation or anation or direct substitution)
[Co(NH3)5Cl]2+ + H2O ? [Co(NH3)5(H2O)]3+ + Cl- aquation
[Co(NH3)5(H2O)]3+ + NCS- ? [Co(NH3)5NCS]2+ + H2O anation
[PtCl4]2- + NH3 ? [PtCl3NH3]- + Cl- direct substitution