Inner sphere or coordination sphere Figure . inner and outer spheres of attraction in coordination compounds XII U5 Coordination XII U5 Coordination - - - - . The primary valences are non-directional while the secondary valences are directional. The geometry of the complex is determined by the spacial arrangement of the groups which satisfy the secondary valence.
For example, if a metal ion has a secondary valence of six, it has an octahedral geometry. If the secondary valence is , it has either tetrahedral or square planar geometry. The following table illustrates the Werner's postulates. Complex Groups satisfy the secondary valence (non-ionaisable, inner coordination sphere) No.
of ionisable Cl - ions in the complex (outer coordination sphere) No. of moles of AgCl formed = no. of moles of ionisable Cl - CoCl .6NH NH Cl - AgCl CoCl .5NH NH & Cl - Cl - AgCl CoCl .4NH NH & Cl - Cl - AgCl CoCl .4NH NH & Cl - Cl - AgCl . .
Limitations of Werner’s theory: Even though, Werner’s theory was able to explain a number of properties of coordination compounds, it does not explain their colour and the magnetic properties. Evaluate yourself : When a coordination compound CrCl .4H O is mixed with silver nitrate solution, one mole of silver chloride is precipitated per mole of the compound. There are no free solvent molecules in that compound. Assign the secondary valence to the metal and write the structural formula of the compound.