Figure 4.

Comparison of the proton Mims ENDOR spectra of P1_H, P2_H, and P3_H recorded at magnetic field positions corresponding to the Z^– transition and visualization of the spin density distributions in P1_H, P2_H, and P3_H calculated by DFT. The ENDOR spectra were recorded at 20 K and pulse lengths of 16 ns were applied. To compensate for blind spots, three ENDOR spectra with τ values of 120, 180, and 240 ns were averaged in all cases. Although calculations predict the spin density to localize on the central unit in P3_H as shown in the figure, solvent effects or changes of the geometry in solution might lead to localization of the triplet state on any one of the three units.