CoSO₄Cl.5NH₃ exists in two isomeric forms ‘A’ and ‘B’. Isomer ‘A’ reacts withAgNO₃ to give white precipitate but does not react with BaCl₂. Isomer ‘B’ gives a white precipitate with BaCl₂ but does not react with AgNO₃. Answer the following questions.

(i) Identify ‘A’ and ‘B’ and write their structural formulas.

(ii) Name the type of isomerism involved.

(iii) Give the IUPAC name of ‘A’ and ‘B’.

(i). Isomer ‘A’ reacts with AgNO₃ and gives white precipitate, as the complex consists of Cl it reacts with the AgNO₃ and gives the precipitate of AgCl and the reaction will be:

White

Hence isomer ‘A’ is

Similarly, in case of isomer ‘B’ it reacts with BaCl₂ and gives white precipitate and it is obviously BaSO₄ and the reaction will be:

White

Hence, the isomer ‘B’ will be

(ii)In this case, the counter ion (Cl^-) in the complex salt is itself a potential ligand and displaces the ligand (SO₄) which can then become the counter ion, therefore, it is a form of ionisation isomerism.

(iii) IUPAC name of isomer ‘A’-Pentaamminesulphatocobalt (III) chloride

And‘B’-Pentaamminechlorocobalt (III) sulphate.