Question

In which of the following coordination entities the magnitude of Δ₀ (CFSE in octahedral field) will be maximum?

(a) [Co(CN)₆]^3- 

(b) [Co(C₂O₄)₃]^3-

(c) [Co(H₂O)₆]³⁺ 

(d) [Co(NH₃)₆]³⁺

(At. No. Co:27)

Answer 1

Correct option (a) [Co(CN)₆]^3-

Explanation :

When the ligands are arranged in order of the magnitude of crystal field splitting, the arrangement, thus, obtained is called spectrochemical series. Arranged in increasing field strength as

It has been observed that ligands before H₂O are weak field ligands while ligands after H₂O are strong field ligands.

CFSE in octahedral field depends upon the nature of ligands. Stronger the ligands larger will be the value of Δ_oct.