Next, to further probe the chemical bonding interactions, the DFT computed electron density was analysed by the quantum theory of atoms in molecules (QTAIM) method. The QTAIM approach is based on the topological analysis of the physically observable electron density, and is thus theoretically independent of the computational method the C 1 -Si bonds). The total computed shift tensors are presented both before (in Table ) and after (in Table ) taking into account these rotations. Table : Calculated and experimental shift parameters for the proximal (denoted by p) and distal (denoted by d) -SiMe 3 group of Yb III (CH(SiMe 3 ) 2 ) 3 in the Haeberlen convention after a three-site fast exchange averaging of the shielding tensors. The shielding tensor is computed according to 2 where the magnetic susceptibility tensor has been computed with the SO-CASPT2 method and the hyperfine tensors are either from the SO-CASSCF or DFT(PBE0) methods. Long-range contributions has been accounted using the semi-classical point dipolar equation according to eq. SI10. It is instructive to examine the breakdown of the shifts into the contributions given in Eq. (1). The FC contribution is negligible in all cases, due to the very limited transfer of the unpaired spin density to these atoms over two, three or four bonds. The intra-molecular PCS is more significant, and is consistently larger for the proximal ligand than for the distal ligand, for all three nuclear species, which is a straightforward consequence of the former being in closer proximity to Yb than the latter. This conclusion is also true in the presence of rotational dynamics, where upon rotation about the C 1 -Si bond, the three methyls on Si 2 are on average closer to the Yb ion than those on Si 1 . The same trend is seen for the more dominant PSO contribution, which for the same reasons is consistently larger by up to one order of magnitude for the proximal ligand. Finally, the long-range PCS is also dominant, due to the large magnetic anisotropy of Yb(III) in this complex. A comparison between the proximal and distal ligands reveals more comple trends than for the intra-molecular PCS, due to the packing of molecules in the crystal lattice.