What is the coordination number of the central metal ion in the complex ion $[\text{Fe}({\text{H}}_2\text{O}{)}_6{]}^{3+}$?

Solution

1. The complex is $[\text{Fe}({\text{H}}_2\text{O}{)}_6{]}^{3+}$.
2. The ligand is water (${\text{H}}_2\text{O}$), which is a monodentate ligand.
3. There are 6 water molecules attached to the iron ion.
4. The coordination number is $6\times 1=6$.
5. Hence the answer is (C).