In the variable-field Raman spectra (Fig. , S7), several apparently field-dependent features are observed in this area as well, in particular, strongly field-dependent features at 230 and 234 cm -1 and a less field-dependent peak at 242 cm -1 . It should be noted that the Raman spectra were obtained by excitation at 532 nm. At this wavelength, the Co complex shows a strong absorption and we can therefore assume that near-resonant Raman spectra are recorded, which particularly enhances the signals of local vibrations of the anion. The shift of the peak frequency with field is rather small, compared to what would be expected for the Zeeman splitting of a pure magnetic resonance transition. Interestingly, further peaks are visible in the Raman spectrum at around 835 cm -1 (1B), and around 1075 cm -1 (1C). The energy of the former feature is rather independent of magnetic field strength. In contrast, the latter signal has a stronger field-dependence consistent with a pure magnetic resonance transition.