Question

In which of the following octahedral complexes of Co (at. no. 27), will the magnitude of Δ₀ be the highest?

Options

• [Co(CN)₆]³⁻

• [Co(C₂O₄)₃]³⁻

• [Co(H₂O)₆]³⁺

• [Co(NH₃)₆]³⁺

Answer 1

[Co(CN)₆]³⁻

Explanation:

The magnitude of Δ₀ is highest in [Co(CN)₆]³⁻ because CN⁻ is a strong field ligand, causing the largest crystal field splitting. The other ligands \[\ce{(C2O^{2-}_4, NH3 and H2O)}\] are weaker field ligands, resulting in smaller Δ₀ values.