VBT - Inner vs. Outer Orbital Complex (Coordination Number 6)

Configurations: $$\begin{aligned} d^2sp^3 &\implies \text{Inner orbital complex (Strong field ligand)} \\ sp^3d^2 &\implies \text{Outer orbital complex (Weak field ligand)} \end{aligned}$$

Concept: Determines whether an octahedral complex utilizes lower-energy inner d-orbitals or higher-energy outer d-orbitals for bonding, heavily governed by the pairing ability of the incoming ligands.

Notation:

• $$d^2sp^3$$ = Inner d-orbital involvement (low spin state);
• $$sp^3d^2$$ = Outer d-orbital involvement (high spin state).