The values for the average magnetization of the Fe-N 6 and Fe-C 6 centers show the selective oxidation of the iron centers during the sodiation of the material. The change in magnetization is further presented in Figure . The full process has been reported in detail in an earlier publication. To summarize, as the carbon coordinated, low-spin iron center is oxidized first, the average magnetization decreases linearly from 1.02 µ B to 0. in the type of functional used in this study.