Fig. 3: Calculated 57Fe NRVS and PKS vibrational modes.

a Comparison of experimental (black line) and calculated (red line) 57Fe NRVS spectra of complexes 1–3. Individual transitions are depicted by red vertical lines. b 57Fe PVDOS along x (red line), y (blue line), and z (brown line) axes, for complexes 1–3. The x axis is defined along Fe-Fe bond, and z axis is perpendicular to the [Fe2Q2]+ core. c Representation of calculated PKS normal modes for complexes 1–3. For clarity, only the [Fe2Q2]+ cores and coordinating N atoms are shown.