Crystal field stabilization energy (CFSE)
Coordination Compounds · Chemistry
Study notes
Calculate CFSE for [CoF₆]³⁻ (high-spin d⁶) and [Co(NH₃)₆]³⁺ (low-spin d⁶). Step 1: Co³⁺ is d⁶. F⁻ weak-field → high-spin: t₂g⁴e_g². Step 2: CFSE = (4 × −0.4 + 2 × 0.6)Δ₀ = −0.4Δ₀. Step 3: NH₃ strong-field → low-spin: t₂g⁶, CFSE = 6 × −0.4Δ₀ = −2.4Δ₀ (+ 2P pairing cost). Step 4: Low-spin gains far more stabilization — that's why CN⁻/NH₃ complexes are so stable!