Question

In which of the following octahedral complexes of Co (at no. 27), will the magnitude of D0 be the highest?

• A. [Co(C2O4)3]3–
• B. [Co(H2O)6]3+
• C. [Co(NH3)6]3+
• D. [Co(CN)6]3–

Answer 1

Answer: (D)

$Co(CN)6$3–

Answer 2

CFSE depends on the relative magnitude of crystal field splitting, Do and pairing energy and in turns Do depends upon the field produced by ligand and charge on the metal ion. The order of increasing crystal field strength is C2O43– < H2O < NH3 < CN–.

Thus the (4) option is correct.