Primary Valence
In Werner's theory, the ionisable valence of a metal, equal to its oxidation state and satisfied by negative ions.
Unit
Dimensionless
In depth
Primary valence corresponds to the charge that must be neutralised by counter ions outside the coordination sphere. These ions are held ionically, dissociate in solution and are non-directional, so they contribute nothing to the geometry of the complex.
Examples in the real world
Cobalt's primary valence of three in CoCl₃·6NH₃, satisfied by the three ionisable chloride ions.