In the planar model A 0 , the two variants of the ground state IS3 configuration with triplet configurations on the ligand, LS2 and HS3, are found within 15 kcal/mol. The two alternative intermediate spin configurations IS1 and IS2 lie within 11 kcal/mol. The remaining electronic structure types, LS1, HS1 and HS2, are destabilized by more than 24 kcal/mol. Notably, the electronic structures of HS1 and HS2 have negative HOMO-LUMO gaps, i.e. appear to be excited states with respect to IS3.