Figure 4.

A key “correlated pair” of orbitals from broken-symmetry calculations on L^Me,iPrFeNNFeL^Me,iPr, showing that there is β spin more localized on the π* orbital of N₂. (S_αβ is the value of the overlap integral between the α and β orbitals.) This is consistent with antiferromagnetic coupling of an N₂²⁻ bridge to two Fe²⁺ ions.