Q. In which of the following coordination entities the magnitude of Δo (CFSE in octahedral field) will be maximum? (at. no. Co = 27)
A) [Co(C₂O₄)₃]³⁻
B) [Co(H₂O)₆]³⁺
C) [Co(NH₃)₆]³⁺
D) [Co(CN)₆]³⁻
Explanation
[Solution from source] For the same metal ion (Co³⁺), Δo depends on the ligand's place in the spectrochemical series, where CN⁻ is the strongest-field ligand here, well above NH₃, H₂O and oxalate. So [Co(CN)₆]³⁻ has the largest splitting. [Co(NH₃)₆]³⁺ is a strong-field complex too, but ammonia splits less than cyanide. Answer (4).
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.