Figure 13.

Energy level scheme showing the effect of the reduction-induced change in the ligand field on the spin state energies of the ${\text{Fe}}_{\mathrm{O}}^{\text{IV}}$ site in the absence of exchange interactions (left and middle column) and in combination with the exchange interactions (right column). The spin values indicated are the local spins (S_b) for the ${\text{Fe}}_{\mathrm{O}}^{\text{IV}}$ site (left) and the coupled spins (S) for the dinuclear center (right). The (5/2, 1) 7/2 level has been aligned with the S_b = 1 levels for comparison. The splittings in the left and center columns were evaluated using a ${\text{Fe}}_{\mathrm{O}}^{\text{IV}}-\text{OH}$ mimic, using different ${\text{Fe}}_{\mathrm{O}}^{\text{IV}}-\text{OH}$ distances as described in section 4.3. The exchange splittings in the right column correspond to the J(5/2, 2) = 135 cm⁻¹ and J(5/2, 1) = 69 cm⁻¹.