(i) write the IUPAC name of the complex `[Cr(NH_(3))_(4)Cl_(2)Cl`
What type of isomerism is exhibited by the complex `[Co(en_(3))^(3+)]`?
(en = ethane-1,2 diamine)
(ii) Why is `[NiCl_(4)]^(2-)` paramagnetic but `[Ni(CO)_(4)]` is diamagnetic?
(At no: Cr =24, Co =27, Ni =28)

Explanation

(i)`[Cr(NH_(3))]CI_(2)[CI]`
(ii) `[Co(en_(3))]`+ show opticla isotmerism
(iii) `[NiCI_(4)^(2)Ni+2=[Ar]3d^(8)4s^(@)`
CI is weak ligand hybridisation =`SP^(3)` pairing not possible hence paramgnetic in nature
Ni+2 has 2 unpaired e = hence this complex is paramagnetic
`Ni(CO_(4))]`
Ni=[Ar] 4 s 2 3 d8
CO is strong field ligand.Hence pairing occurs sp3 hybridised
Ni has zero unpaied electron this complex is diamagnetic