Developing Metals 3: Substitution of Ligands

Question 1

Definition of ligand substitution

Answer 1

Reaction where one ligand is replaced by another ligand

Question 2

When ligands are of similar size in a substitution reaction what is the effect on the coordination number

Answer 2

No change in coordination no.

Eg. [Co(H2O)6]2+ +6 NH3 —>

Co(NH3)6]2+ +6 H2Oy

Ie. Coordination remains as 6

Question 3

When ligands are of different size in a substitution reaction what is the effect on the coordination number

Answer 3

coordination number may change

Eg. [Co(H2O)6]2+ +4 Cl- —>

Co(Cl)4]2- +6 H2O

Coordination number: 6 —> 4

Question 4

Explain why the coordination number changes when substitution of different sized ligands occurs

( can use Cl- and H2O to help explain )

Answer 4

Cl- is bigger than H2O = only enough space for 4 Cl- ligands rather than 6