Crystal Field Stabilization Energy Calculator: T...

What is Crystal Field Stabilization Energy?

Crystal Field Stabilization Energy (CFSE) is the extra energetic stability gained by a transition metal complex due to the splitting of d-orbitals in a ligand field. When ligands approach the metal, they split the five d-orbitals into lower (t₂g) and higher (e_g) energy sets. Electrons preferentially occupy lower orbitals, releasing stabilization energy.

💎 CFSE Calculator

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📐 Formula

CFSE = n(t₂g) × (−0.4Δₒ) + n(e_g) × (+0.6Δₒ)

Δₒ = crystal field splitting energy. Each t₂g electron contributes −0.4Δₒ; each e_g electron contributes +0.6Δₒ. Subtract pairing energy for low-spin configurations.

📝 Worked Example

[Fe(CN)₆]⁴⁻: Fe²⁺ has d⁶ configuration. Strong field CN⁻ → low-spin: t₂g⁶ e_g⁰
CFSE = 6×(−0.4Δₒ) + 0 = −2.4Δₒ (maximum for d⁶)

📝 How to Use

Enter Metal and Oxidation StateSelect transition metal (Fe, Co, Ni...) and its charge (2+, 3+...).

Enter Ligand FieldChoose ligand strength — strong field (CN⁻, CO) or weak field (F⁻, H₂O).

Determine Spin StateHigh-spin (weak field) or low-spin (strong field) configuration.

Calculate CFSEView CFSE in units of Δₒ and interpret complex stability.

❓ FAQ

What is the spectrochemical series?

A ranking of ligands from weak to strong field: I⁻ < Br⁻ < Cl⁻ < F⁻ < OH⁻ < H₂O < NH₃ < en < NO₂⁻ < CN⁻ < CO. Strong field ligands cause large Δₒ and favor low-spin.

Does higher CFSE mean more stable complex?

Generally yes — higher CFSE means electrons occupy lower energy orbitals, contributing extra thermodynamic stability (reflected in larger formation constants Kf).