Orgel Diagrams are correlation diagrams which show the relative energies of
elecronic terms in transition metal complexes. They are named after their creator,
Leslie Orgel. Orgel diagrams are restricted to weak ligand fields (i.e. high-spin
complexes). Because Orgel diagrams are qualitative, no energy calculations can
be performed from these diagrams.
Orgel diagrams only show the symmetry states of the highest spin multiplicity instead
of all possible terms, unlike a Tanabe-Sugano diagram. Orgel diagrams will, however,
show the number of spin allowed transitions, along with their respective symmetry
designations.
In an Orgel diagram, the parent term (P, D, or F) in the presence of no
ligand field is located in the center of the diagram, with the terms due to that electronic
configuration in a ligand field at each side. There are only two Orgel diagrams,
one for d1
, d4
, d6
, and d9 configurations and the other with
d
2
, d3
, d7
, and d8 configurations.