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Topic: Calculating LFSE  (Read 17280 times)

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Offline SadBloke

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Calculating LFSE
« on: January 31, 2014, 01:40:03 AM »
I'm having some trouble calculating the Ligand Field Stabilizing Energies of transition metals. The first thing I do is determine the oxidation state of the metal and then I input it in this equation:

LFSE = (# of t2g electrons)(.4) - (# of eg electrons)(.6)

Sometimes this works, like when I use it for Fe2+ when it is bound to a weak field ligand and creates a high spin complex.

I get:  LFSE = (4 t2g electrons)(.4) - (2 eg electrons)(.6) = .4

It doesn't work for other atoms, like Co3+. When I use it for Co3+ (in a low spin state) I get 2.4 because there are no electrons in the eg orbitals. When I look it up in my book, the correct LFSE is 2.4-2P.

I know 2P is related to the energy pairing of electrons that destabilize the configuration but I don't know how it factors into the equation or how to calculate any LFSE that contains a 'P' term.

How do I know when to include a P term?

Offline SadBloke

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Re: Calculating LFSE
« Reply #1 on: January 31, 2014, 02:00:21 AM »
I think I understand a little more, now. For every pair of electrons, I need to subtract P (or so it seems).

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