Crystal field theory: splitting in octahedral and tetrahedral fields
Coordination Compounds · Chemistry
Study notes
[Fe(H₂O)₆]³⁺ is pale violet but [Fe(CN)₆]³⁻ is deep red. Explain via CFT. Step 1: H₂O is a weak-field ligand → small Δ₀ → high-spin d⁵ (t₂g³e_g²). Step 2: CN⁻ is strong-field → large Δ₀ → low-spin d⁵ (t₂g⁵). Step 3: Different splitting → different d–d transition energies → different absorbed colours. Step 4: Ligand strength tunes colour — spectrochemical series in action!