An cationic complex has two isomers A and B . Each has one `Co^(3+)`, five `NH_3` , one `Br^(-)` and one `SO_4^(2-)` . A gives a white precipitate with `BaCl_2` solution while B gives a yellow precipitate with `AgNO_3` solution. (a) What are the possible structures of the complexes A and B ? (b) Will the two complexes have same colour ?

An cationic complex has two isomers A and B . Each has one `Co^(3+)`,

1.	An cationic complex has two isomers A and B . Each has one `Co^(3+)`, five `NH_3` , one `Br^(-)` and one `SO_4^(2-)` . A gives a white precipitate with `BaCl_2` solution while B gives a yellow precipitate with `AgNO_3` solution. (a) What are the possible structures of the complexes A and B ? (b) Will the two complexes have same colour ?
Answer» (a) Since the isomer A gives a white precipitate with `BaSO_4` solution , `S0_4^(2-)` ion is present as anion in the complex A . Since B gives a yellow precipitate with `AgNO_3` solution . `Br^(-)` ion is present as anion in it. The two isomers are ionisation isomers and are shows : `[CO(NH_3)_(5)Br]SO_4` `[CO(NH_3)_(5)SO_4]Br` (A) pentaaminebromidocobalt (III) sulphate (B) pentaamminesulphatecobalt (III) bromide. (b) No, the two complexes have different colours. For details, consult Section 6.