Question

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

1. Identify ‘A’ and ‘B’ and write their structural formulas.
2. Name the type of isomerism involved.
3. Give the IUPAC name of ‘A’ and ‘B’.

Answer 1

(i) Isomer A reacts with AgNO₃ but not with BaCl₂, it shows it has CP ion outside the coordination sphere.

Hence, A = \[\ce{Co(NH3)5SO4]Cl}\]

Isomer B reacts with \[\ce{BaCl2}\] but not with \[\ce{AgNO3}\], it shows it has \[\ce{SO^{-}4}\] outside the coordination sphere.

Hence, B = \[\ce{[CO(NH3)5Cl]SO4}\]

(ii) Ionisation isomerism

(iii) ‘A’ - Pentaamminesulphatocobalt (III) chloride

‘B’ - Pentaamminechlorocobalt (III) sulphate