What is the difference between primary and secondary valency of a coordination compound?
What is the prim. and sec. valency of [Pt(NH3)6]Cl4???
The primary valence is the number of negative ions needed to satisfy the charge on the metal ion. In CoCl3 6NH3 the cobalt(III) complexe three Cl- ions are needed to satisfy the primary valence of the Co3+ ion.
The secondary valence is the number of ions of molecules that are coordinated to the metal ion. Werner assumed that the secondary valence of the transition metal in these cobalt(III) complexes is six.
[Pt(NH3)6]Cl4
In this complex the primary valency is 4; and the secondary valency is 6.