Continuous Wave (CW) X-band (ca. 9.4 GHz) spectra were recorded with a Bruker EMX spectrometer fitted with a Super High Q X-band resonator and at Q-band (ca. 33.9 GHz) microwave frequency using a Bruker EMX300 spectrometer. Polycrystalline and frozen solution (9:1 toluene:hexane, 10mM) samples of 1-Eu were sealed in quartz X-band and Q-band EPR tubes in vacuo; samples were lightly ground with a mortar and pestle to reduce the amount of sample decomposition, but we note that some effects due to polycrystallinity remain in the spectra below.