Podcast
Questions and Answers
Which ligands are considered strong-field ligands?
Which ligands are considered strong-field ligands?
- CN- and CO (correct)
- NO2- and CO
- CN- and I-
- I- and Br-
What is the octahedral splitting diagram for the ion [Fe(NO2)6]3- with 5 d-electrons?
What is the octahedral splitting diagram for the ion [Fe(NO2)6]3- with 5 d-electrons?
- Low-spin splitting diagram
- Intermediate-spin splitting diagram
- No splitting diagram is possible
- High-spin splitting diagram (correct)
When does low spin splitting occur in relation to Pairing Energy (P) and the splitting energy ($\Delta$)?
When does low spin splitting occur in relation to Pairing Energy (P) and the splitting energy ($\Delta$)?
- $P > \Delta$ (correct)
- $P = \Delta$
- $P < \Delta$
- $P$ has no effect on low spin splitting
What is the Corrected Crystal Field Stabilization Energy (CFSE) for the low-spin case of Cobalt (III) (d6)?
What is the Corrected Crystal Field Stabilization Energy (CFSE) for the low-spin case of Cobalt (III) (d6)?
What is the formula for CFSE (Octahedral)?
What is the formula for CFSE (Octahedral)?
Study Notes
Strong-Field Ligands
- Strong-field ligands create a larger crystal field splitting.
- Examples include CN⁻, CO, and NO.
- They lead to low-spin configurations in transition metal complexes.
Octahedral Splitting Diagram for [Fe(NO2)6]³⁻
- Iron in [Fe(NO2)6]³⁻ has a +3 oxidation state, resulting in 5 d-electrons.
- In an octahedral field, the d-orbitals split into two sets: t₂g (lower energy) and e₄g (higher energy).
- For 5 d-electrons, the distribution follows: ↑↓ ↑ ↑ (with three in t₂g and two in e₄g).
Low Spin Splitting and Pairing Energy
- Low spin splitting occurs when the crystal field splitting energy (Δ) is greater than the pairing energy (P).
- It favors electron pairing in the lower energy t₂g orbitals over occupying higher energy e₄g orbitals.
- As a result, the complex becomes low-spin with more paired electrons.
Corrected Crystal Field Stabilization Energy (CFSE) for Cobalt (III) (d⁶)
- For low-spin Co³⁺ (d⁶), the 6 d-electrons are distributed as: ↑↓ ↑↓ ↑ (all t₂g are filled, and e₄g has one unpaired).
- The CFSE is calculated as:
- CFSE = (number of electrons in t₂g × -0.4Δ) + (number of electrons in e₄g × 0.6Δ)
- CFSE = (4 × -0.4Δ) + (2 × 0.6Δ) = -1.6Δ + 1.2Δ = -0.4Δ.
Formula for CFSE (Octahedral)
- The formula for calculating CFSE in octahedral complexes is:
- CFSE = (n_t₂g × -0.4Δ) + (n_e₄g × 0.6Δ)
- Where n_t₂g and n_e₄g are the number of electrons in the t₂g and e₄g orbitals, respectively.
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Description
Test your knowledge on the effect of ligands on d-orbital splitting. Learn about strong-field ligands like CN- and CO, and weak-field ligands like I- and Br-. Understand how different ligands influence the size of Δ in d-orbital splitting diagrams.
