Q.Crystal field stabilization energy for high spin d⁵ octahedral complex is

Step 1. High spin d⁵ octahedral configuration: t2g³ eg² (3 electrons in the lower set, 2 in the upper set, all unpaired, per Hund's rule with no pairing forced).

Step 2. CFSE = [nt2g(-0.4) + neg(0.6)]Δ₀ = [3(-0.4) + 2(0.6)]Δ₀.

Step 3. = [-1.2 + 1.2]Δ₀ = 0 × Δ₀ = 0. …

Write the high-spin d⁵ configuration (t2g³eg²) and substitute directly into CFSE = [nt2g(-0.4)+neg(0.6)]Δ₀, remembering no pairing energy term applies since a h …

• Confusing high spin d⁵ with LOW spin d⁵ (t2g⁵eg⁰), which would instead give a large negative CFSE (-2.0Δ₀) plus a pairing energy penalty -- the question specifically asks for the HIGH spin case. …