For calculation of 𝛿 para in the M(THF)1 and M(THF)0 structures, there are several models that can be used to account for the solution 1 H NMR spectra of 1-M showing a 2:1 ratio for the SiMe3 signals. For the M(THF)1 structures, one can consider one SiMe3 group of each hypersilanide ligand on the same side of the M(SiM)3 plane as the remaining THF ligand ("cis") and the other two SiMe3 groups on the opposite side ("trans"), as well as the opposite arrangement (two "cis" and one "trans"). For the M(THF)0 structures, one can consider one SiMe3 group of each hypersilanide ligand closer to the pyramidalized M atom ("proximal"), and the other two further away ("distal"), or vice-versa (two "proximal" and one "distal"). In some of our model structures the assignment is not obvious between the three ligands, thus to address this uncertainty, and to account for dynamic rotation of each of the σ-bonds in the hypersilanide framework, we have used three approaches to account for all the possible scenarios. We define the "plane" as the average plane formed by the four M(SiM)3 atoms, and then determine which non-bound Si atom on each ligand is closest to the plane. In the first approach, these are defined as the group 1 ("in-plane") SiMe3 groups, and the other two as the group 2 ("out-of-plane") groups (see Supporting Information Tables ). In the second approach, we located the nonbound Si atoms that are farthest from the plane to define group 1, whereas the other two Si atoms that are closer to the plane are defined as group 2 (see Supporting Information Tables ). In the third approach, we consider the only remaining option for a 2:1 ratio, which is where the SiMe3 group closest to the plane is averaged with the one that is farthest from the plane to define group 2, and the intermediate SiMe3 group defines group 1 (see Supporting Information Tables ).