# Ligand Field Theory: Why do we use the t2g p-orbitals instead of the t2g d-orbitals in the combination with LGOs [closed]

With the premise that it's the first time that I try to understand the Ligand Field Theory, I'm having issues in fully understanding the MO diagram of a $$\sigma$$-complex, as shown below:

I understand that one should combine orbitals with the same symmetry. My question is: why should one choose to combine the 4p orbitals with t2g symmetry on the side of the metal atom with the t2g orbitals of the LGOs instead of using the 3d orbitals with t2g symmetry of the metal atom with the LGOs?

## closed as unclear what you're asking by Tyberius, Mithoron, Mathew Mahindaratne, Todd Minehardt, JanJan 13 at 15:18

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• The 4p orbitals, as well as the LGOs, are $\mathrm{t_{1u}}$ and not $\mathrm{t_{2g}}$ symmetry. – orthocresol Jan 11 at 18:01
• woops - I've misread it the whole time. Thank you very much. – gionti Jan 12 at 12:33