The same CEST measurement as reported in the main text was carried out at room temperature (298 K). The data in Figure shows the same lines as are reported in the main text, albeit that there are more difficult to distinguish because of their overlap. Note that the magnitude of the CEST effect is stronger at room temperature because of the faster ligand exchange Figure : H NMR CEST spectrum in methanol-d4 recorded under the same conditions as the data reported in Figure of the main text, but at room temperature (298 K). The data shows, that the intermediates 1 and 2 can also be distinguished at room temperature. Grey squares and lineexperimental data; red, blue and green lines are Lorentzian fits.