I am trying to understand the magnetic behavior of materials whose TM (Cr3+ ) has octaheadral crystal field. However, out of six neighbors, 3 neighbors of TM are oxygen and other three are nitrogen. I was wondering how does the presence of N instead of oxygen changes superexchange interactions.
I'd say primarily you need to focus on the orbital overlap (and symmetry), rather than on the element. Small ligands and a more intense orbital overlap achieve strong superexchange between two metal ions. A strong overlap with net cancellation because of symmetry reasons tends to result in ferromagnetic exchange, while strong overlap with no cancellation tends to result in antiferromagnetic exchange, independently of Nitrogen vs Oxygen presence.
http://www.scholarpedia.org/article/Goodenough-Kanamori_rule
Thanks Dr. Gaita-Ariño
I am not sure about how does cancellation effect super-exchange. Can you please elaborate little more on the effect of cancellation ?
PS: I am assuming, by cancellation you mean equal occupancy of bonding and antibonding orbitals.
Thanks again
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