Which complex compound is most stable?
- [Co(NH3)3(NO3)3]
- [CoCl2(en)2]NO3
- [Co(NH3)6]2(SO4)3
- [Co(NH3)4(H2O)Br](NO3)2
Answer
(2) [CoCl2(en)2]NO3
Solution
Ethane-1,2-diamine (en) is a bidentate ligand that forms five-membered chelate rings with the metal.
Chelation increases the stability of a complex (chelate effect).
[CoCl2(en)2]NO3, the only chelate complex, is the most stable.
Answer: (2)