We performed magnetic susceptibility studies for Yb[CH(SiMe We characterized the Yb(III) alkyl complex Yb[CH(SiMe 3 ) 2 ] 3 using pulse EPR spectroscopy that, in combination with computational studies, enables the successful characterization of the spatial and electronic structure of paramagnetic complexes. The continuous-wave (CW) EPR spectrum of Yb[CH(SiMe 3 ) 2 ] 3 (Fig. , blue) was reasonably reproduced by simulation (Fig. , red) by modeling the Yb ion as an electronic spin S = 1/2, with g tensor principal values of g ⊥ = 0.7316 and g ∥ = 7.5698. The spectrum also exhibits a well- A higher-resolution picture can be provided by pulsed EPR spectroscopy, which has evolved into a robust tool for the determination of geometry and electronic configuration of organometallic complexes of paramagnetic d-and f -block metals. In particular, 2D hyperfine sub-level correlation spectroscopy (HYSCORE) allows us to detect magnetically active nuclei (e.g. 1 H, C, Si etc.) that are coupled to paramagnetic centres by hyperfine interaction, due to close spatial proximity to these centres. The technique can separate the isotropic (primarily Fermi-contact) and anisotropic (primarily spin-dipolar) parts of the hyperfine interaction tensors that are linked to the electronic properties of the systems (e.g. metal-ligand spin density transfer), and bonding between the nuclei and the paramagnetic centre. The HYSCORE spectrum of Yb[CH(SiMe 3 ) 2 ] 3 (Fig. and Fig. ) reveals the presence of hyperfine coupling to protons in the CH(SiMe 3 ) 2 alkyl ligands. From the simulation of the HYSCORE spectrum a single 1 H hyperfine tensor was determined to have