JEE MainChemistryCoordination Compounds
Consider the following cobalt complexes: A : [ Co ( H ₂ O )₆]²⁺ B : [ Co ( H ₂ O )₆]³⁺ C : [ Co ( en )₃]³⁺ The correct increasing order of their crystal field splitting energy ( ₀ ) is
Options
- AB < A < C
- BA < B < C
- CA < C < B
- DC < B < A
Correct answer
B. A < B < C
Step-by-step solution
The magnitude of crystal field splitting energy ( ₀ ) depends on both the oxidation state of the central metal ion and the strength of the ligand field. For the same metal and ligand, a higher oxidation state of the metal results in a larger ₀ . Comparing A and B, both have H ₂ O as ligands, but B has Co ³⁺ while A has Co ²⁺ . Thus, ₀ of B > A. For the same metal ion in the same oxidation state, a stronger ligand produces a larger ₀ . According to the spectrochemical series, ethylenediamine (en) is a stronger ligan