`CoSO_(4)Cl.5 NH_(3)` exists in two isomeric forms 'A' and 'B'. Isomer 'A' reacts with `AgNO_(3)` to give white precipitate, but does not react with `BaCl_(2)`. Isomer 'B' gives white precipitate with `BaCl_(2)` but does not react with `AgNO_(3)`. Answer the following questions.
(a) Identify 'A' and 'B' and write their structural formulae.
(b) Name the type of isomerism involved.
(c) Give the IUPAC name of 'A' and 'B'.

Explanation

(i) As isomer A reacts with `AgNO_(3)` to give a white precipitate, Cl must be present in the ionization sphere.
As it does not react with `BaCl_(2)`, `SO_(4)^(2-)` must be present in coordination sphere.
`therefore` Formula of `A=[Co(NH_(3))_(5)SO_(4)]Cl` (coordination no. of Co=6)
As reactions are reverse for isomer B, formula `B=[Co(NH_(3))_(5)Cl]SO_(4)`
(ii) Ionisation isomerism
(iii) A = Pentaamminesulphatocobalt (III) chloride , B = Pentaamminechloridocobalt (III) sulphate.