variable temperature continuous wave (c.w.) EPR spectra were collected on frozen solutions at Xband frequency (ca. 9.4 GHz) between 5 K and 40 K, and simulations to model spectra were performed with EasySpin. For the sample of in situ-generated was observed (Figure ); no features were seen in other spectra that could be confidently assigned to 1-Ln (see Supporting information Figures ). previously. The only features observed in X-band EPR spectra of 10 mM Me-THF frozen solutions of 1-Ln for Ln = Ce and Nd <15 K were assigned as parent 2-Ln by comparison of the EPR parameters obtained with those reported in the literature (see Supporting Information Figures ). For 1-Pr a complex pattern of features was observed <15 K that could arise from hyperfine coupling with 100% abundant I = 5/2 141 Pr nuclei, which requires further study (Figure ); interestingly, for the parent non-Kramers 4f 2 Pr(III) complex 2-Pr isotropic frozen solution spectra were obtained <50 K, with a single g-value (3.320) (Figures ). However, this feature was not observed in variable temperature powder X-band EPR spectra of 2-Pr (Figure ) and magnetic data suggests the ground state is singly-degenerate (Figure ). We attribute the lack of features that can be confidently assigned to 1-Ln in the spectra obtained to a combination of incomplete reduction, facile thermal decomposition, and the weak intensities/EPR silent nature of 1-Ln; 1-La is the exception as there are no 4f electrons present and the La(III) precursor 2-La is diamagnetic.