This document discusses molecular orbital theory for octahedral complexes. It presents sigma and pi molecular orbital diagrams showing the interaction between metal d orbitals and ligand group orbitals. The diagrams show the splitting of the metal d orbitals into t2g and eg sets, as well as the effects of pi acceptor and donor ligands on the molecular orbital energies.

1. Molecular Orbital (M. O.)
Theory (Octahedral
Complexes)
Dr. Mithil Fal Desai
Shree Mallikarjun and Shri Chetan
Manju Desai College Canacona Goa

2. A σ M. O. for octahedral complex
t2g, eg
a1g, t1u, eg
a1g
t1u
t*
1u
a*
1g
e*
g
eg
a1g
t1u
Δo
t2g
Ligand group orbitalsMetal orbitals

3. a1g, t1u, eg (σ)
Ligand group orbitals
A σ and π M. O. diagram for octahedral complex
(n-1)d t2g, eg
(ns) a1g
(np) t1u
t*
1u
a*
1g
e*
g
eg
a1g
t1u
Δo
t2g
Metal orbitals
t*
2g
t2g (π*)
t2g (π)
MX6 molecular
orbitals
π acceptor ligand

4. (n-1)d t2g, eg
a1g, t1u, eg (σ)
(ns) a1g
(np) t1u
t*
1u
a*
1g
e*
g
eg
a1g
t1u
Δo
t2g
Ligand group orbitalsMetal orbitals
t*
2g
t2g (π)
A σ and π M. O. diagram for octahedral complex
t2g (π*)
MX6 molecular
orbitals
(t1u, t1g, t2u, t2g)
π donor ligand