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.