Ligand Field Theory: σ/π Bonding, Orbital Splitting, and Spin States

All flashcards

Ligand field theory (LFT)

A molecular-orbital description of bonding and orbital energies in transition-metal complexes that builds on crystal-field ideas.

Ligand group orbital (LGO)

A symmetry-adapted combination of ligand orbitals that can interact with metal orbitals of matching symmetry.

π backbonding

Transfer of electron density from metal orbitals into unoccupied ligand π* orbitals.

High-spin configuration

An arrangement with more unpaired electrons, often favored when octahedral splitting is small.

Spectrochemical series

An experimentally derived ordering of ligands by the splitting they produce.

Quiz questions

1. In an octahedral complex, which d-orbital set lies higher in energy?Answer: The $e_g$ set, consisting of $d_{z^2}$ and $d_{x^2-y^2}$.
2. In a tetrahedral complex, which d-orbital set lies higher in energy?Answer: The $t_2$ set, consisting of $d_{xy}$, $d_{xz}$, and $d_{yz}$.
3. What is the usual effect of ligand-to-metal π donation on octahedral splitting?Answer: It tends to decrease $_o$ and is associated with weak-field behavior.
4. What property does the spectrochemical series arrange ligands by?Answer: The size of the orbital splitting they produce.
5. Which metal orbitals are mainly involved in octahedral π interactions?Answer: $d_{xy}$, $d_{xz}$, and $d_{yz}$.