Question

What type of structural isomers are [Co(NH₃)₅ Br] SO₄ and [Co(NH₃)₅ SO₄]Br? Give a chemical test to distinguish the isomers. 

Give a chemical test to distinguish between [CoBr(NH₃)₅]SO₄ and [Co(SO₄)(NH₃)₅]Br. What kind of isomerism do they exhibit?

What type of isomers are [CoBr(NH₃)₅]SO₄ and [Co(SO₄)(NH₃)₅]Br? Give a chemical test to distinguish between them.

Answer 1

Ionisation isomerism due to the exchange of ions inside and outside the coordination sphere. [CoBr(NH₃)₅]SO₄ and [Co(SO₄)(NH₃)₅]Br are ionisation isomers.

Test with Barium Chloride (BaCl₂) Solution:

The aqueous solution of [CoBr(NH₃)₅] SO₄ will give a white ppt. with BaCl₂ solution insoluble in conc. HNO₃, confirming the presence of free \[\ce{SO_4^2-}\] ion. An aqueous solution of [Co(NH₃)₅SO₄] Br will not give this test.

\[\ce{[Co(NH3)5Br]SO4 ⇌ [Co(NH3)5 Br]^2+ + SO^2-}\]

\[\ce{BaCl2 + SO4^2- -> \underset{(white ppt.)}{(BaSO4 ↓)} + 2Cl^-}\]

\[\ce{[Co(NH3)5 SO4]Br ⇌ [Co(NH3)5 SO4]^+ + Br^-}\]

\[\ce{BaCl2 + Br^-  -> No ppt}\]