Coordination Compounds – Solutions

1) Explain the bonding in coordination compounds in terms of Werner’s postulates.

Solution

There are two types of valencies shown by central metal ion in a corrdination compound: i) Primary valency ii) Secondary valency

1. Primary valency corresponds to oxidation number and secondary valency corresponds to corrdination number.
2. In the complex [Co(NH₃)]Cl₃ , primary valency of Co is three and secondary valency is six.
3. Primary valency is satisfied by negative ions(anions) while secondary valency is satisfied by ligands which can be neutral and as well as negative (positive in rare case).

In [Co(III) (NH₃)₆ ]Cl₃. six NH₃ ligands satisfy secondary valencies while three Cl-ions satisfy primary valencies.