Organometallic compounds, perhydrocarbyls in particular (MR n with M = metal; R = hydrocarbyl), often adopt unusual geometries or bonding patterns due to their low coordination numbers and the associated electronic consequences in metal-carbon bondings. These patterns continue to engage the broader community in understanding how preferences in geometric structure relate to the often complex electronic structure and reactivity in these compounds. As an example, among diamagnetic compounds, carbons with single bonds that exhibit significant π character to metals show specific deshielded nuclear magnetic resonance (NMR) chemical shifts and associated reactivity, indicating that alkyl groups are often better described as both σ-and π-donors to the metal (Figure ). Reduced J C-H coupling constants for these carbons, and associated specific structural distortions, provide evidence for agostic interactions. Similar bonding peculiarities are also found in compounds with metalcarbon multiple bonds. The prototypical example is Ta( --CH t Bu)(CH t 2 Bu) 3 , which contains a highly deshielded C signal and a very low J C-H coupling constant for the formally sp 2 hybridized Ta=C carbon. These signatures are consistent with an α-CH interaction, better described as an additional π-donation from the α-carbon to the electron deficient d 0 metal centre. Peculiarities in geometric structure from X-ray diffraction analysis are also observed in monomeric lanthanide perhydrocarbyl complexes, Ln[CH(SiMe 3 ) 2 ] 3 (Ln = Y, La, Ce, Sm, Lu 10 ) that contain three short Ln ... C γ contacts between one Si-CH 3 group of each of the three proximal -SiMe 3 groups (Fig. ). The Ln ... C γ contacts result in lengthening of the Si-CH 3 bonds close to the lanthanide by ∼0.04 Å with respect to the other Si-CH 3 groups, indicating that these proximal Si-CH 3 groups interact with the lanthanide. This interaction helps to satisfy the high coordination numbers required to isolate these f -block homoleptic complexes; a strategy that also facilitates isolation of Yb[C(SiMe 3 ) 3 ] 2 , 11 Ln(AlMe 4 ) 3 , and Ln[C(SiHMe 2 ) 3 ] 2 . Recent studies of Lu[CH(SiMe 3 ) 2 ] 3 10 indicated that the Lu• • • C γ interactions are not a result of γ-C-H agostic interactions (2-electron donation from a C-H bond to an electron deficient metal centre), but are rather due to a three-centre-two-electron (3c-2e) interaction between the Si-Me bond and Lu. In other words, the Lu• • • C γ interaction is best described as a pseudo bridging Lu-Me-Si group (Fig. ), analogous to Al-Me-Al observed in dimeric AlMe 3 or Ln(AlMe 4 ) 3 . The critical data in that study were a combination of high quality X-ray diffraction results, variable temperature 1 H and C NMR spectra in solution, as well as J-resolved 1 H- C and Si Magic-Angle Spinning (MAS) solid-state NMR spectra. The experimental results were reliably reproduced using both wave-function based and density functional theory (DFT) models of Lu[CH(SiMe 3 ) 2 ] 3 , and natural bond orbital (NBO) analysis showed that the charges on C α and C γ are negative, while the charges on Si β and H γ are positive. This analysis was consistent with the proposed bridging Lu-Me-Si group to describe the Lu• • • C γ interaction. Extending this analysis using similar NMR methods to other Ln[CH(SiMe 3 ) 2 ] 3 is however challenging, because most lanthanides contain a partially filled f-shell in their +3 oxidation state. The resulting paramagnetism perturbs the magnetic properties of the nearby nuclei, making data acquisition and interpretation complicated at best, and typically impractical in most instances. Similarly, while electron paramagnetic resonance (EPR) could offer a potential alternative for this class of compounds, the signals are typically not detectable at room temperature using routine continuous wave (CW) methods due to the short electronic spin relaxation times and large hyperfine couplings. However, both fields have seen impressive recent progress. In solid-state NMR, fast MAS and broadband adiabatic irradiation sequences allow for measurements on such samples and in EPR, new EPR pulsed tech-niques were developed for f -block metal complexes. In parallel, the recent advances in quantum chemical/DFT methods and dedicated formalisms now allow us to interpret NMR and EPR data in terms of the spatial and electronic structure. In this study, we showcase a methodology to assess the detailed electronic structure of a prototypical compound, namely Yb[CH(SiMe 3 ) 2 ] 3 , by combining state-of-the-art EPR, NMR and computation (Figure ). We first synthesized and isolated a series of Yb[CH(SiMe